My first attempt using zero also like that. Its heat whenever, the switch on heat, the glitch off. After cool down its running fine again.I actually am currently experiencing this with one of my Nephew's switch lites that I recently modded. The last few days both nephew's switch lites have been glitching and booting to CFW fine (albeit a bit slower than I might like) but they were also my first consoles to have XIAO 2040's in them. One still seems to be fine, but the other boots straight to OFW, as if there is no glitch occurring.
Both are on 2.73 firmware, and after letting it sit for a while (read as several hours) I tried turning it on and got it to glitch successfully one time. Turned it off, then back on again and it booted to OFW.
I plan to swap out the XIAO 2040 with a Waveshare 2040-tiny once it comes on Tuesday, till then, I guess the XIAO might be failing?