Switch frozen and screen turned black - what to do?

[switcherjoe]

Hi everyone,
I tried to use mame2003 with cheats in Retroarch and put the file cheat.dat into the mame2003plus folder. For some reason mame/retroarch didn't like it at all and Switch was nearly frozen, then I tried to close Retroarch and it was completely frozen ("Programm will be closed" and nothing happened). So I removed Switch from the docking station, the screen turned black. I tried to reboot it, hold the power button for 30+ seconds, but it doesn't go on again. I use AutoRCM, so the RCM mode should be activated with the black screen, but TegraRCMGUI doesn't recognize Switch as it seems ("No RCM device detected"). Any ideas what to do now? I tried to enter the recovery mode (+/- and power button), but it doesn't work as it seems with AutoRCM. Please help, many thanks!!!!
P.S. I am using FW 13.1.0 with the Atmosphere and sigpatches for it.

 

[switcherjoe]

I am not sure what happened, but I managed to get into RCM again.
What I did:
1) tried many times holding all possible button combinations for 30+ seconds - nothing helped
2) pulled out the SD card - no reaction
3) tried to reinstall again the APX driver in TegraRCMGUI - no reaction
4) tried to use fusee-gelee firebaseapp and then tried another USB3.0 port, and FINALLY TegraRCMGUI showed the device in RCM mode!