Why not try the (cheap) CMOS battery since what's next is the mainboard, cables and more. Those are much more expensive.
To repeat. Try the cheap stuff first.
I recently spilled some coffee in my laptop, which unfortunately have caused some failures regarding the boot up.
When my DC cable isn't plugged in, i am not able to boot the laptop. However, if i plug my cable in, boot it, and unplug the cable there is no problem.
Could it be the CMOS battery, or some circuit on the motherboard which took some water damage during my little coffee-incident?
I haven't experienced any checksum failures, nor clock resets.
At the moment i'm not able to provide you with the name of the computer, but it's a Zepto Znote (Unknown danish brand) and it's about 3 years old and is running Windows 7.
Thanks in advance!