I doubt it is the motherboard. If you get into BIOS, the motherboard is mostly good. Does it boot a floppy?
I will try to say something positive here. You can get very good service from a SFF machine if you understand that expansion is very limited. Don't let it overheat and it can outlast the warranty period.
Kept it vertical and well ventilated.When these units overheat, the PSU and hard drive takes the beating. But a bad motherboard can happen.
New egg and others with sell you a refurbished e Machines SFF for an attractive price, warranty tetra. If he likes the machine, he might consider buying another one and keeping the old old for spare parts, it ever needed.
Under $240 warranty extra.
Dual core Emachines Intel (or AMD)
Windows 7 Home Premium 64-Bit
500 GB HDD
Keyboard & Mouse NVIDIA graphics
Picture is from Newegg.