I'll tell you because I just did this. I had to "reflow" the GPU because the heatsink that Acer used on the Graphics Processor sucks. There is a gap between the processor and the heatsink *no direct contact.
So to fix this, you will have to strip the entire laptop down to the bare motherboard. I mean everything has to come off. Remove any old thermal grease from the heat sink, CPU, and GPU. Remove CPU as well. Now if you have a heat gun, you can use this first on low settings to warm up the GPU. Then you gradually increase temps to between 200-420C. Then you do the reverse and let it cool down slowly. *Recommend cleaning the fan while you are at it.
After the GPU is cooled, then reapply new thermal grease. I recommend arctic silver but any brand should do. Apply a pea to lima bean sized droplet on the head of the GPU and a slightly larger droplet of thermal grease to the CPU. Also apply some directly to the heat sink.
*Optional; insert a sliver of copper as a shim between the GPU and heatsink. I used a coin that I cut, and smoothed as my shim. I used a copper coin because it is a great conductor of heat and allows the heat to escape quickly.
Then put it all back together, and cross your fingers.
I will say this prior to doing all this I tried changing the motherboard coin battery as well as flashing the BIOS and all sorts of things. only the GPU reflow worked. This is probably a temporary solution to the problem but it did get my laptop going again!
A couple of videos to help guide you along that I personally used to get a good idea how to do this before I tried.
https/www.youtube.com/watch?v=LIaZ8I7TxDM
https/www.youtube.com/watch?v=BVHAlzm5iJ8
https/www.youtube.com/watch?v=BVHAlzm5iJ8
Note, many of these are not the same model that you have but they do show the basic process for doing this job. Some of these videos demonstrate risks like using a heat gun around memory chips and the like, disregard that and follow a rigid rule of getting the motherboard out.
Also, if you don't have a heat gun, it was said that an oven can be used, but I recommend picking up a cheap heat gun!
Just in case it's your cmos battery:
https/www.youtube.com/watch?v=cTYLnsteLkc