How to change power supply?

ibrahim morawej, your Acer has an external power supply. You can get those at places like this. Check your existing one with a multimeter and see what the output is. If your power supply is sufficient you may have greater issues. Check the flow sheet I attached from the manual, which you can download from here My number one suggestion would be to change your battery. If that is not working then you are looking at the DC power board (daughter board B) something like this last but not least, if none of the before mentioned works, time to think about a new mother board, but start with a systematic approach. You could also try to clear the CMOS by removing the CMOS battery for a few hours, but it's not guaranteed to work.It involves dismantling the AA1 to get access to the motherboard so it's only recommended for experienced users. Use the instructions below at your own risk. Source

"There are four memory chips on the motherboard, nicely aligned next to each other. A few millimeters to the right are two triangles with a small C1 printed next to them. Connect both triangles using conductive material, effectively shorting them, and press the power button. The CMOS has been reset. It is obvious but the AA1 must be turned off before doing the procedure." Good Luck and let us know.