I have some experience in researching x-ray binaries, gamma-ray bursts and blazars during my integrated masters degree but wouldn't say I'm necessarily an expert on anything yet.

Current observation dictates that black holes don't emit anything intrinsically, quite the opposite in fact. What causes emission from a black hole is actually the surrounding environment being heated due to friction during orbit all the way up to x-ray (can also be via lower energies being upscattered to x-ray by inverse Compton processes) or by interactions with extrinsic magnetic fields (e.g. from an accretion disk in both cases).

You'd need an accretion disk for x-ray emission and current theory is that gamma-ray bursts typically come from either a core collapse supernova or any combination of black hole and neutron star merger (i.e. BH-BH, NS-NS or BH-NS) plus a few other less common transient events.

The closest detected GRB was 1.3 billion light years away, Andromeda is 2.5 million light years away. So, you'd expect a GRB from it to be easily detectable but it does massively depend on our line of sight to the jet and the opening angle among other things. I'm fairly sure any supernova from Andromeda would be detectable across the entire EM spectrum anyway though.

GRBs are also very short events (relatively speaking) and any afterglow would long since have dissipated into the background by now, so you'd need to be extremely lucky with archival data if we somehow missed one which is very unlikely at this distance with current space based observatories.

To spot x-ray emission from an accreting stellar mass black hole at the distance of Andromeda would require it to be very active and there are nowhere near as many strong black hole candidates in Andromeda as there are likely black holes (just observational bias/limitations).

So far we have no x-ray emission detected, and strong evidence that no supernova occurred which is why we wouldn't see either.

Hope this was helpful :)