White screen after Apple logo

I have a MacBook Pro 17’” late 2011 (MacBookPro8,3).

Problem: When I boot my Mac, after the Apple logo and after loading about 70% of the progress bar, only a white screen appears (slightly darker than the home screen) without going further (the Apple logo and the progress bar disappears).

I don’t know if I did something with an un-install of a teleworking program (Cisco AnyConnect) which it could not be completely uninstalled and installed with the necessary settings and I wrote in the terminal the commands I found here: Cisco AnyConnect Manual uninstall Mac OS

Also sometimes on the same day it disconnected the Bluetooth speaker I had connected on its own.

I closed the lid to put it to sleep and after about 2 hours I went to open it there was a white screen (while the lid was closed).

I have tried and entered Recovery Mode once, I entered Utilities I ran Disk Utility - First Aid for both Macintosh HD and MacOS Base System and managed to get into High Sierra. After working for about an hour, the screen froze, I closed it from the power button and since then I have not been able to open it again. I have done everything (reset NVRAM, safe mode, SMC reset, internet recovery ...) and it remains the same problem without being able to even enter Recovery Mode.

I ran the Apple Hardware Test many times and my results show that it has no problems (no trouble found). Also in the Hardware Profile, displays all the computer information.

The only upgrade I made was the RAM (16GB). I also put the original ram (4GB) but it remains the same problem.

I don’t know what to do. I would greatly appreciate any idea.

Thanks in advance and sorry if I got tired.