|Usually the power supply is the first victim in an electrical storm. Are you sure the motherboard is what is bad. |
If the motherboard is the bad component then as you may know, the version of Windows on your hard drive is keyed to the original motherboard. That means you would need to replace with the same motherboard. That can be expensive.
In the future you should use a surge protector to protect against that type of damage.
If you can borrow a power supply that is compatible I suggest trying that as a start.
I'm not sure the technician that told you the motherboard was bad had any way to determine that for sure.
Not turning on at all would indicate a bad power supply.