AMD really aren't doing too well in the processor marketplace right now.
Their next big thing was supposed to be FX, but I think they underestimated the level of support they would get from the motherboard manufacturers in terms of the motherboard manufacturers going out of their way to make the FX chips a success.
The major motherboard manufacturers all make boards for both Intel and AMD and they don't really care if they need to make more of one type or less of another. Intel is the easiest thing for them, because Intel doesn't cause support calls for FX.
If people just buy Intel, things get easier for the motherboard makers, so they have an incentive for people not to buy FX. That, I think, is why they feel it is OK to bend people over who do buy FX. They just don't want you to do it, so they generally have a bad level of support for it and everybody knows that. They hope you just read the reviews and buy Intel instead.
Anyway, I think all that is kinda unfair to AMD, but it was AMD's bad call that made all this happen. They shouldn't have made a BIOS update that would make the new chips work on the old boards.
Sure, there is some subset of people who would have had to buy a new motherboard if they wanted to use FX and it wouldn't be as simple as doing a BIOS update with the motherboard and processor you already have to allow you to switch out that processor for an FX one, but I don't think many people are doing that anyway.
For example, I have a Phenom 2 x4 chip myself and I could do a BIOS update and then replace it with an FX 4100 or something, but I really have no intent to actually do that. The gain for me is just not that much.
It is much more likely that a FX chip will be purchased at the same time as a motherboard as part of a new computer. That works OK if the person building the computer has old AMD chips laying around, which OEM builders do, but not well if the person buying the new parts doesn't have that.
Basically, AMD either knowingly or unknowingly screwed the hobbyist on this. Either way is pretty unforgivable.
If they just said the old boards weren't compatible with FX and people had to have a new type of board (AM4 or something) to work with FX, then all these problems would have been avoided.
Anyway, none of that really helps you. I just wanted to give you a bit of background and to say that it isn't entirely AMDs fault. They made a call that would work if the motherboard makers chipped in, but they didn't actually chip in. Thus the marketplace failure.
Anyway, at this point I am pretty much out of things to try. It seems like two different kinds of the same general item just have both been bad and I don't really have any good reason to believe it is one thing or another thing.
You had a tech look at it and they didn't see anything immediately wrong with it with what seemed to be a basic quick look over for incorrect connections or so.
You may have to just bite the bullet and take it to a computer shop, either that or consider trying a 3rd round of parts.