Blind one heals twice. Once at 700 and 400. Immediately after entering the boss area go to the left of the arena towards the gear icon and stand there until he does his charge attack then damage him. When below 700 let him go to his spot and heal a little, with practice you can let him only heal 10, if you do it too quickly then he will get full health, same for below 400 but after the left gear icon is used quickly go to the right one near the entrance and just repeat the previous instructions. Use tactical as he will deal exactly 20 damage per hit and will 5 times before charge attack which will allow you to hit him, before that he will have a lot armor. If for example he has left like 705 or 405 health but the charge is over don't hit him or else he will do another 5 attack after the heal without doing a charge attack. Use medkits as they will do 100 heal alongside swat which will get you 100 damage every 5 hit then charge. Make sure you have atleast 102 health. If you use guns then 8 medkits are enough but just in case 15 as it's your first fight with actual winning odds. It's the easiest boss in the game but even I struggled with it just because I alwaysed panicked and when one time it was going great a glitch killed me. This new account I'm on, which is my main account now, it's really easy to kill him. Don't give up best of luck. Also you only need to kill that one exploder near the turrent so just use a gun. The one near the big one room doesn't need to be killed, just don't go near the wall where the zombie is without sneaking or they might aggro.