Thanks for the advice but it doesn't work, holding in the power button just cycles the mi 11 to the mui logo and then fastboot logo, then goes back to mui logo again then fastboot.it doesn't matter if I press power on it's own or power and up/down keys it always ends up with the fastboot logo which suggests maybe a corrupt or incorrectly applied wrong partition.
Someone mentioned installing fastboot driver from mui unlock application would fix a 'destroyed' mi 11 of another user and I've already responded to that that I have a mi 9 which as soon as I put in fastboot mode my pc detects it immediately, swap to my mi 11 and it isn't being detected at all and I use same process, same cable, and same pc.
I accept there is always a risk of using roms, I also appreciate all the time and effort the developers put into providing these, but this seems to be an issue affecting multiple device models.
Hopefully a solution is found soon but from later posts it looks like it's going to take some time