First of all I bought my first Xiaomi phone last week, a Mi 10T Lite, currently with MIUI 12.0.2.
Today the phone got fully discharged so I connected the charger. I’m using the original charger socket but with another/non-original cable (5A, purple colour on sockets) because it’s longer. I left it for around 30 minutes like that and I couldn’t ever turn it on. The LCD displayed a battery icon with a bolt symbol in it.
I swapped the cable for the original one (orange colour on sockets) and instead of a bolt symbol, it displayed 2% and I managed to turn it on.
After it was on, I swapped the cables again and it’s charging normally.
What the heck?
TLDR: Phone doesn’t charge if using a cable other than the original one but only when it’s fully discharged. After turning the phone on, it charges just fine.