My computer gets warm, then it shuts off automatically, lately shut down and can not get it to come back on even with new battery and adapter. A local computer man advised it was the motherboard?

Your problem is a bad Processor fan. Have the fan replaced first. The fact that the unit works for awhile and shutsdown points to the fan.

This seems to be a common problem with laptops over a couple of years old. Dust gets trapped in the copper fins and the fan of the CPU heatsink and reduces the efficiency of the cooling, which results in regular power off's by the laptop as it gets over it's upper temperature setting. The fix is relatively easy, just remove the heatsink unit, blow it clean with compressed air, clean the old CPU heatsink paste off with isopropyl alcohol (IPA) and spray a thin film of heatsink paste on the CPU. If the cleaning does not work, replace the fan.

If I could be of further assistance, let me know. If this helps or solves the issue, please rate it and give a testimonial for my response

Thanks, Joe

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_8b8c2cd6ce148309