Hi to all.
Same issue here! (probook455g7, Italy), after the assistant initiated update of the last week.
A sudden change from a perfectly working state into a deadly useless state occurred.
After several days of contacts with HP phone assistance, and following multiple suggested interventions, nothing worked.
Since the machine is out of warranty, the proposed solution is a rather expensive motherboard replacement.
This would certainly solve the issue (until the next official virulent BIOS update). Given the origin of the problem, I believe HP should reconsider and provide genuine assistance to their customers.
However, if anyone could kindly provide more details about the flashing operation, location of the chip, connection to the chip, etc., it would be greatly appreciated.