Hello,
Got a couple of SSRs off of ebay recently, since it was the only place I could find DC SSRs. Fotek, rated for 40A, undoubtedly counterfeit, but I took a chance on it being a quality clone. However, they arrived in extremely poor packaging and one was quite banged up. I tested the other and it burned out in seconds while switching 15A (rated 40) despite being hooked up to a properly sized heat sink.
The seller is offering a replacement. Naturally I wouldn't ever use those without thoroughly testing them first, but I was wondering if it's even worth giving it another try. Thus I took one apart and uncovered the power FET to check its rating, but I can't find anything of the sort online.

It says NEC on the first line, 412 on the second, and the part number on the third line is A1009. Does anyone have any idea what this FET is and where I could get a data sheet?
If anyone has any links to good instructables for DIY DC relays, I'd appreciate seeing those. Thanks!