I typically have about 55 hours run time on my Apple Watch 4. But I pushed it this week and just forgot to put on charge since Sunday morning. So last night about midnight I went to just look at the time and it was dark. Put it on charge and the time came up with a red flashing lightning bolt and the time. Kept it on charge for about 30 minutes and the face was flashing with this red lightning bolt. It was also very warm. Had to do a reset with holding both buttons down for 15 seconds then the Apple symbol came up. After 10 minutes the AW4 was back to normal. The charge on it after the reset showed about 5%. Left it on the charger until this morning. All back to normal again. Did not lose any of my setups.