Precision 5520 booting problems

Hi, i’m using a Precision 5520 and lately i’ve been having some serious problems. It all started about two weeks ago when i was using my laptop and it suddenly shut down. I later found out it was a thermal shutdown. I proceeded to clean the air vent which was covered with dust and it solved the problem. After a few days i noticed that my laptop was taking forever to come up. I pressed the power button and the power light came up but the laptop screen was blank and the fan was off. It took about five minutes until the laptop fan just came on and the screen suddenly shows the dell logo and started booting up. After that the laptop was perfectly fine. It was still as fast as it was before except from the long boot up time. I tried to restart the laptop but it came up immediately. I shut it down and waited for five minutes but it still came up immediately. I thought it was a one time problem so i shut it down and left it for a few hours. When i turned it on, it took about four minutes to boot up. I’ve tried everything i found online. I even removed the latest updates and resented my pc but it still had the same issue. I updated all the drivers with the ones i found on dell website and it the problem still continued. In fact, the time for it too boot up has increased over the past one to two weeks. It now stays at a little over 12 minutes.

Last week i noticed another problem. When my laptop goes into sleep mode or i don’t use the keyboard for to long, the keyboard backlight doesn’t come up. I firstly noticed while watching a movie that when i touched the touchpad the light didn’t come up as it usually did. I then proceeded to press the F10 button which controls the keyboard light and the laptop just froze. It took about 10 minutes until it booted to the blue screen error page with the Driver_Power_Failure or something like that. it then takes another 20 minutes before it restarts. and continues normally. I’ve really tried everything. I eventually found an error that said:

The embedded controller (EC) did not respond within the specified timeout period. This may indicate that there is an error in the EC hardware or firmware or that the BIOS is accessing the EC incorrectly. You should check with your computer manufacturer for an upgraded BIOS.

I’ve updated the bios and almost every driver on the laptop but the problem just won’t stop. I’m guessing both problems are somehow related.

The last weird thing i noticed is that i put my laptop to sleep a few days ago and the screen turned off but the power light and the fan were still on. I tried to wake it up but nothing was working. I had to wait until the laptops battery died before i charged it and later turned it on. 

Please i want to know if anyone knows what is wrong with my laptop or at this point i should just get another one. Thanks.