I don't think it's the country's fault if there are some bad apples.
The best advice would be to buy from sellers with good reputation.

I am not an electronics expert but maybe you mean MOSFET?

Yeah (Or basically, ne of many types of transistor), but what type, or what is an equivalent I could order? That was what I was asking.

Seems there are two different types used on the board here.

I'd say it is something equivalent to 2N4922, see this image or search for other pictures that show the numbers better. There may have been many different but compatible transistors used in different packages.

But make sure there is nothing else broken, or the new transistor will blow up too. (Kind of like having device with a blown fuse, the fuse blowing up is not the problem but a symptom of it. Replacing the fuse does not fix the problem, and the new fuse will blow up too).

I wonder if they are ooposing polarity devices, NPN/PNP or n-channel/p-channel

It goes 223, blown, 223, 219 - so the blown one may be a 219 ... whatever that is

They do look like the style of mosfets, but maybe not.

Found that same image, and I'll say they are complementary 2n4922 & 2n4919

The 219 / 2n4922 (blown) is NPN , normally that would be the positive output, so if the output capacitor for that channel is shorted, it would pass continuous DC current to the speaker

I think you're both spot on with that. I'll grab some as I doubt they cost very much and it's best to replace all four of them. Strange how I couldn't see the numbers in the image linked (As I already searched before posting) until you pointed them out... Been thinking for a while I am due to see an optician.

I will of course check and replace other components, the caps will be fixed first. Should still weigh up cheaper than it would have done otherwise, even if I don't get my money back.

Thanks!

Take a good sharp big picture of the area, just in case something else blows and you can't read markings any more. At least SMD resistors and transistors can be "decoded" what they are.

I'd say replace the output capacitor ... I suspect it's shorted - may as well replace both, as they don't need to be super-spec low ESR, just standard.

I don't know about the output capacitor, but at least the electrolytic below Q5 appears to have a hole like it was hit with something sharp. If the metal is punctured through I suggest replacing it.

Oh, believe me, I'm replacing those. They were the first thing I noticed because when I got it the area was covered in electrolytic fluid so I had cleaned the card a day before taking that picture. I have quite a few spare caps in stock so I can do that quickly, but I may as well wait and just do it when I replace the transistors.

I think the two big ones are the output capacitors, one for left channel and one for right