UBOOM L - Blinking Power Light And No Functionality After Successful Firmware Updates

Hello ~ I recently purchased the UBOOM L, which switched on and paired with my phone successfully.

I wished to downgrade the firmware to Oluv's 0.4.5, which appeared to have work correctly, however when I now try to switch the unit on, I get a flashing power light and cannot pair my speaker with a device. I re-flashed the firmware back to 0.5.0, but that has not solved the issue.

I've tried a speaker reset by holding the power button for eight seconds, and also using the reset switch on the back of the unit.

Can you assist please?

Thank you!!