So I ordered this thing of AliExpress, miraculously enough it arrived unscathed and I set to work trying out various games and software on it. All seemed to be working fine, until I was trying out a DOS MIDI player (dosmid). After about half an hour of testing various MIDI files, it seems to have locked up during play, the screen went blank and there was some very weird sound output going on. I figured it had just hardlocked, so I turned it off and on again, only to be met with the same black screen and weird noises. Ctrl-Alt-Del won't make it restart, and no amount of power cycling would clear the problem. I've had experience running DOS on laptops before, and sometimes a power off from the button won't completely shut down the unit and you have to remove the battery to get it to fully power off and cold boot. So I dismantled it and unplugged the battery, leaving it for about half an hour for everything to discharge and then put it back together. No dice, same issue. I thought maybe the OPL3 sound card had locked up or something, so I removed that, and while it stopped the sound the machine still wouldn't boot. I put it back in, turned it on and the sound came back as before. I experimented with some of the button combinations, and discovered that it still responded to the commands to turn the speakers on and off and also enable/disable turbo mode, which changed the speed at which the sound was generated. I decided to leave it sitting on for a while, in the hope that it was just still hobbling along trying to play the MIDI file, and now the sound has stopped but it still won't reboot.

I'm stumped at this point, and any help would be appreciated!