Question Gigabyte motherboard will not boot after upgrading CPU

[FastFred]

I have a Gigabyte GA-MA69G-S3H with an AMD Athlon 64 X2 5000+ 2.6 GHz CPU, 8 Gigs of Kingston DDR2 ram, a Thermaltake 500 watt PSU and running Windows 10 Pro. 2 nights ago windows did a update on the computer. The screen was locked and I couldn't do anything. Just that little circle going around. I watched it for 3 hours till I gave up and went to bed. The next afternoon I checked the computer and it was on the windows 10 logon screen. I logged on and everything was fine.
Today I received the new AMD Athlon II X2 270 3.4GHz cpu that I bought on Ebay. It was sold as a new unused open box cpu without the heat sink or fan. I have my suspicions that it may of been used. I removed the power cord and hold the power button down to discharge any stored power. So I install the new cpu with thermal paste and the heat sink fan. Make sure the cpu fan is plugged in, press the power button. The monitor screen stays black, all the fans come on, CD-Rom clicks and the DR-Rom light flickers, floppy drive clicks. I have to remove the power cord to turn off the power. Tried this a few times with no luck. Removed the new cpu and re-installed the old cpu with the same results. checked the pins on both cpu's and they are in perfect condition. I've re-installed the old cpu a few times, checked all connections remove and re-installed the RAM. Removed motherboard battery, tested it and it still read 3.2 volts. Jumped the jumpers to reset the CMOS a few times. I can not flash the bios to the latest version because I can not get the computer to boot with the old cpu to do that. Called my friend the computer genius and he can't figure out what is wrong. The motherboard probably needed the newest version of the bios before installing the new cpu but that is too late now. I even used the Hard Drive from another computer ( exact same Gigabyte motherboard and exact same WD T hard drive ). This hard drive with Windows 10 pro doesn't have the latest update from 2 days ago. Still no change.

 

[DMAN999]

Have you tried installing the old CPU then resetting the cmos via the jumper?
Also unplugging the power cord and removing the battery may help.
Installing a new CPU would not change the BIOS, but if the BIOS doesn't support the new CPU it would obviously not boot with the new CPU installed.
You could also try re-flashing the BIOS with the original CPU installed then update it.

 

[FastFred]

I removed the power cord, pressed the power button until the power was discharged. Removed the battery and reset the cmos with the jumpers with the old CPU installed. Still didn't boot up. I removed 3 of the 4 RAM modules (2 gigs each Kingston DDR2). It will now boot up and I was able to flash the Bios to version F8E per the Gigabyte website's note for the AMD Athlon II X2 270 CPU. Still no change, It will only boot up with 1 RAM module. I switch out the module with the other 3 modules. Doesn't make a difference which one is installed as long as it is only 1 module installed. So the computer will now boot up with either CPU but only as long as 1 RAM module is used. I tried the HDD from an identical computer (same motherboard, same HDD and Windows 10 pro except this HDD doesn't have the latest update to Windows 10). Still will only boot up with only 1 RAM module. All 8 gigs (4 RAM Modules of 2 gigs each) were fine before installing the newer CPU and the latest Windows update.