Bullet R1 V2 stuck on Err9998 after firmware downgrade (RoasTime 6.17)

Hi everyone, I’m looking for help recovering my Bullet R1 V2.

I was running the latest firmware/RoasTime version, but I started experiencing IBTS crashes around ~185°C during roasts. In an attempt to fix this, I tried downgrading to RoasTime / firmware version 6.17.

During the downgrade/update process, the control panel showed Err9998 and the process froze. RoasTime then showed the roaster as “not connected.”

Since then, every time I power on the Bullet:

The display shows Err9998

The fan runs

The machine becomes unresponsive/frozen

RoasTime cannot detect the roaster (shows “roaster not connected”)

It looks like the firmware update may have been interrupted and the machine is now stuck in this state.

Has anyone experienced this or know the recovery procedure (firmware recovery)?

Any help would be appreciated. Thank you.