Asus Zenbook UX300 - Completely Dead - Service center fixed in 10m

Today I was working on my Asus zenbook UX330 (a new 7th gen, all one in case) when it crashed (possibly due to Linux drivers - that's my issue and separate to this). Not a problem I held power for a few seconds and it rebooted, the Asus bios screen flashed and I decided I had enough for the day anyway so held power down again switched it off (bad timing to switch it off during bios booting?. Off it went and I went home.

At home I couldnt get it to switch on again, it wasn't hot or anything. I tried multiple power sockets. I tried the hold power button for 60 seconds without and with AC (and 20sec, 10 sec etc..). No nothing, not even a flashing light indicating power or recharge, completely dead, no indicators no nothing. I even gave it a good old fashion bump. Dead.

Taxi called and off I went I took to the local service center who instantly came up we'll need to take it off you for 2-3 weeks blah blah blah, I cut them off and pleaded with them to try a hard reset - something I had read in taxi related to a different laptop with detachable battery, after a little bit of pushing they relented and walked to the back where the techies where. They came back ten minutes later and my Ubuntu hard drive unlock screen was up, bingo, fixed - power at 79% too and it's functioned fine ever since.

I am wondering what they did and how I can do it myself next time. They did just remove the screws and disconnect the battery - is that the hard reset procedure for intergrated battery zenbooks? I tried to ask but they couldn't communicate this to me - my knowledge of local language is poor - but at this point I was just thankful. This fixed my problem so Im grateful, but wasting an afternoon in taxis and having to fight a battle for same day service isn't something Im eager to repeat (perhaps next time I'll get a more stubborn jobsworth who insists on RMA). tl;dr how to do a hard reset on intergrated battery zenbooks?

On reflection, if there is a condition where corruption can happen for abruptly losing power during the bios boot then this is pretty poor on Asus, my confidence in their reliability is dented to say the least.. (but at least its not a ****ty Acer)