Generally speaking yes it's a bad idea to run non-original or unofficial firmware *except* in my case (and seems with others), downloading the source for the original/official miner from official bitmain github, building it per included instructions, then running it on T9+ essentially bricks the cards. One by one.. The longer you leave it running & auto-rebooting, the more cards it kills. It seems to happen if someone upgraded to the autotune firmware which must flash updates to the boards then the older software thinks the boards are corrupt so it tries to flash them & it appears to flash them wrong or with wrong version etc.  I didn't make note of what version of firmware these shipped with but if it wasn't the autotune one that's available on their site it's possible anyone flashing the pre-autotune firmware might end up in the same boat.