I tried flashing the rom, reboot to A partition (the one which was unused) then ended up stuck on a boot animation (the electric sphere) for more than 30 minutes, so I decided to hard reboot the phone, load TWRP and boot to partition B (stock firmware) and I was lucky that the stock ROM somehow recovered.
I followed these steps:
- fastboot boot twrp-recovery-image.img
- factory reset (the one with the swipe)
- advanced wipe: wipe dalvik/art cache
- flash zip to unused partition A
- select partition A
- reboot system on partition A
- 30 minutes and more of boot animation
Did I do something wrong?
Update
Solved with:
- fastboot boot twrp.img
- chose slot A (Bliss rom)
- factory reset, format data
- reboot system
then ROM boots in less than a minute