JBL Charge 3 Bluetooth Speaker Woes

A neighbour owns this Bluetooth speaker, which he gladly bought after my recommendation. I have its smaller brother, the Flip 4, which is amazing, to say the least.
Now, JBL has equipped these speakers with Connect/+ tech that merges playback from its multiple product portfolio (Charge, Flip, Xtreme, Pulse).
To link the Flip 4 to Charge 3, the latter must be updated with the JBL Connect app. Upon completing the process, the damn thing cannot boot. It powers, blinks for 3 seconds, then powers off. I understand the update corrupted its normal operation, and this is made worse by little help on the internet.
The device can’t even play nice to button combinations that should reset it.
Anyone who has experienced this madness? Solution?

Holding the power and volume low button mostly works

Tried this, didn’t work. Thanks tho.
The speaker is back to the retailer now. Probably awaiting a replacement.