ATTiny acting weird about diybms HOT 2 CLOSED

Hello, this could be many things, I'd suggest:

1. Check wiring on the ISP header and pins
2. Check for solder bridges between pins on the ATTINY
3. Check you run "burn bootloader" against the attiny with the correct settings (this burns the fuses)
4. Ensure you never select an external crystal on the Arduino menu

from diybms.

I checked and checked again and everything was right. But I noticed the side 2 of the ADUM 1250 was powered and the 2 inputs were disconnected and it pulled the SCK and SDA input of the ATTiny to the ground. I was stupid, trying to program the ATTiny with the I2C bus pluged, surely it doesn't make sense at all as the ISP and I2C use the same pins for the clock and SDA.
Now I know, don't try to program the ATTiny with I2C connected (VCC included)

from diybms.