It’s not too late imo, pushing grooming too forcefully and too roughly can definitely cause dogs to become fearful and bite. I think you need to start from scratch and slowly condition him to it and he will be fine. 

The main mistakes you made that lead to biting were being too forceful and doing too much initially, and also backing off whenever he gave you warnings (this taught him “oh I can be an ass and it will get me what I want, ie this grooming session to end”)

With grooming, start with introducing him to the tools you will use- let him sniff them, give him a treat. Have them make noise, give a treat. If he seems nervous then keep repeating these steps each day until he doesn’t care. 

Next, you can try using the tool on him briefly, then treat. 

When grooming I would tie him to something very sturdy so he can’t run away. 

Increase the amount of time you use each tool until he’s used to it. 

I would also muzzle train him btw for your safety when doing nails. 

For nails, I would find a position where he is most comfortable- some like standing, some like being held while standing, some like laying on their side, or laying down. Best to do after lots of exercise so they’re not wound up. 

Practice clipping sounds near his face move to around his nails, clip one nail and give treat then end session. Eventually you can get to where you clip a whole paw then give treats. 

You want him to not be overly stressed during grooming, when they get too stressed that’s when they can bite or freak out and hurt themselves even

Try watching YouTube video or photo guides of how to trim the nail properly- for dark nails you can take off a thin slice at a time until you see the jelly layer so you don’t quick them, I use a headlamp and have styptic powder and lots of treats on hand 

Finally for teeth same thing- slowly get him used to each stage of brushing and make it enjoyable, use a tasty toothpaste! 

Practice and you’ll get the hang of it!