There's no need to buy a new BIOS chip, just use nvflash and reflash the original VBIOS for it by using the same force flash command you used to flash the incorrect VBIOS. If nvflash can't see the card anymore, well, you're SOL, flip the card for someone who knows how to fix it.
You have an LHR card, the ASIC used is different (GA102-202), you can't just flash the original non-LHR VBIOS on it, there are hardware level differences to reduce Ethereum hash performance, it's intentional to slow down cryptocurrency miners from hogging gaming GPUs. Something similar occurs with old GTX 780 cards, the newer manufacture models are silently designated Rev. 2 and use the updated GK110B processor from the 780 Ti in it, flashing the original GK110 780 BIOS on it will result in a brick. Was messing around with one this week.
BIOS updating isn't for rookies, if you're not sure of what you're doing, don't do it. That's the golden rule.
The Ventus PLUS is LHR, 100%. Unless you have the older, original Ventus. If you're going to open your card, it's easy to tell. Non LHR is GA102-200, LHR is GA102-202. It's laser etched onto the chip.