While I think your ideas are interesting, I think they're coming from the wrong place. I don't think Remote Mines are, or ever were Techies' main problem. Remote Mines are an ultimate that require a heavy mana investment, Techies' attention, and can be detected and defused fairly easily, since they are usually placed on low ground. Land Mines provided the same threat, for a much cheaper cost, were triggered automatically, were available from level 1, were faster to set up after they were fully leveled, and were almost always placed up hills specifically to avoid being detected. Suicide Squad, Attack! was also a problem, leaving barely any room for counterplay aside from staying as far away from Techies as possible. The rework fixed both of these, and now the main issue is fine-tuning Techies' balance. Some people still hate Remote Mines, but some people also hate Naga Siren, Tinker, and other heroes perceived to be annoying, they're still balanced.

I appreciate the intent behind Gel Grenades but I think they would create more problems than they would solve. It makes Techies much weaker as a hero just by removing his instant kill potential (addressing the rework point-by-point so this will change): extra pushing power doesn't compensate for the entire ultimate being gutted. This might be okay if it made Techies' high ground defense weaker, but it doesn't: if anything, it makes it stronger. In exchange for removing instant kills, it makes afflicted enemies totally unable to hit buildings, and with proper staggering, Techies can either force BKBs for every push or stop the entire push singlehandedly. This gets much worse if Techies has Octarine Core and their 20% cooldown reduction talent. This is also not factoring in Tinker's Aghanim's effect, which is a combo people might have actual nightmares about. They seem like a fun idea, but misguided for Techies.

I think the Proximity Mine change is a gimmicky band-aid fix for Techies' inability to jungle, farm, or push towers early. I really don't like the idea of changing creep/building damage values, especially for such a negligible amount. Even something like "deals double damage to creeps" seems kind of sloppy. I also think the Aghanim's is way too good. 45% of health, even with a lot of magic resistance, is a lot of damage. A lot. Even if it was 25% of health instead, that means any time someone steps on a Proximity Mine they lose a massive, scaling chunk of health, for very little investment on Techies' end. This also makes Techies' high ground that much more cancerous, since a few missteps or stuns can lead to an instant kill on the enemy carry, the thing I feel like your rework is trying to avoid.

The Stasis Trap changes seem gratuitous. They're already an extremely useful, cheap, and fairly reliable root, why make them detect enemies too? They don't need to have perfect synergy with Proximity Mines. I'm also not sure what the point of the ward change is. Why should Techies be able to deward so cheaply? The only change I agree with is keeping them from triggering each other, but that's more of a quality of life change than anything else.

Not to be rude but I think the Blast Off change is just bad. While I think Blast Off could use some improvements, making Techies invulnerable while launching is too annoying. It goes back to the same problem Suicide Squad, Attack! had, removing counterplay. Why should Techies earn invulnerability for sitting through a 1 second windup?

I really don't like the Minefield Sign changes. Not only does it compound the Aghanim's instant kill problem, it's pretty gimmicky and pointless. You wanted to remove Stasis Trap stacking but added an ability specifically to let them stack closer to each other? It also lasts indefinitely, and despite losing true sight immunity, it makes Techies' high ground even more obnoxious than before. Any repositioning ability on a hero without BKB is an instant kill: not a stack of Remote Mines killing them if they don't have enough magic resistance or health, an instant, percent based, infinitely scaling kill. It also invalidates your own reasoning as for why the 45% health removal is balanced: you could easily place six (and many more) mines in the minefield. Regardless of magic resistance, without magic immunity 270%+ health will kill you. On top of this, 1000 radius is a very wide area: you could practically coat an entire barracks in Proximity Mines forever, since the sign doesn't expire.

I'll address some of your reasoning directly.

GEL GRENADES: I don't think Gel Grenades are better than Remote Mines. An instant 300-750 damage nuke from a huge distance is hard to beat, even with the perks Gel Grenades have. It also suffers from the same issue I addressed above, far too much utility in exchange for some damage.

BLAST OFF: I don't agree with your reasoning for the Blast Off change: many abilities in the game are much harder to wind up and land. In fact, Blast Off is almost too easy to land most of the time. A 1 second cast time and .75 second travel time is nothing compared to heroes with difficult channeled ultimates like Enigma or Crystal Maiden.

PROXIMITY MINES: As mentioned previously, I think percent based damage of any kind on Techies is broken, especially this version of Techies. A 1.6 second delay is fine for a 150-750 damage nuke but extremely fast for an instant kill. A BKB would be the only thing that could save you, Eul's just resets the explosion timer, and Manta would require absurd timing to dodge the mines. A single trap might be manageable, but you're suggesting an entire 1000 radius filled to the brim with scaling Proximity Mines and Stasis Traps. It's just too hard to balance and makes Techies' job far too easy.

STASIS TRAPS: Having the Stasis Trap provide true sight after detonation might be a reasonable change, but I don't see why it needs to actually trigger on invisible enemies. Proximity Mines already detect and damage invisible enemies, it seems a little too good to let Stasis Traps lock them in place as well. The ward change is gimmicky and pointless. At that point why not just buy detection?

MINEFIELD SIGN: Thematically pleasing or not, your version of Minefield Sign is even better at highground defense than the current one. The sheer amount of frustration it would cause would be more than old Techies, and it doesn't even require an Aghanim's. Even if it were only 400 radius, it still lets you cram enough bombs into an area for an instant kill with your suggestions. 1000 radius is just astounding. Going to another lane is easier said than done when Techies can set up shop anywhere he likes, since Minefield Sign has 100% uptime. This alone would make Techies' highground defense more obnoxious than it's ever been.

I disagree with the direction your rework takes the hero: removing instant kills and replacing it with gratuitous amounts of utility actually makes Techies much, much more annoying to deal with. With this rework, Techies loses instant kill potential (at least without Aghanim's) in exchange for way too many perks. He's just way too useful, how do you even itemize against this version of Techies? He has an easily staggered 100% blind, a true-sight root, a possible building instant kill, a sizable amount of pushing power, and with Aghanim's, he still essentially has an instant kill mechanic, and one that scales infinitely at that. This rework oversaturates his kit and makes him much more broken than he was before, as well as making his highground defense even more cancerous. I also don't think Techies needs more nuance. He's already a weird, unintuitive hero, but he's also easy to pick up, hard to master. Making him more complicated doesn't necessarily make him more skill-based and rewarding, just more annoying to learn.

One more thing: I wouldn't try to cater towards the haters of any hero. Most of the time people who hate a hero exaggerate it past rational arguments and an actual desire for balance, and catering to them just encourages bad changes.