I hope you get it back working without having to purchase a Main board or Power board, but you need to take this warning seriously, and get protection for your printer.
I want to take this opportunity, to Highly Recommend to all who read this, it is way cheaper in the long run to purchase a power (battery) backup with voltage regulation and good surge protection built in.
My SP540v and the computer work-station that drives it are both powered through an APC smart UPS 2200net, with power conditioning that protects connected loads from surges, spikes, lightning, and other power disturbances.
This unit saved my printer when we were in a medium rain event, and all of the sudden, BAM, lighting hit
very close by, all the lights flickered and the power went off, other items not connected to the UPS experienced problems, however, I noticed all the lights on the smart UPS control panel flashing as it was dealing with the spike in power and then went into battery back up mode for a few minutes, when the power came back on, the smart UPS switched back into normal mode.
I read on signs101 a while back that someone here purchased a used one on ebay, so I searched ebay and got a good deal also, mine didn't have batteries when purchased, but that was a good thing, it made shipping cheaper, and I was able to purchase 4 new batteries, so I will be well protected for at least a few years as batteries last about 3-4 years.
Consider yourself WARNED!!!!