I have the firmware installed on my t9; the t9+ firmware but the miner doesn't hash; its as if control board doesn't send the command to the cards on the miner. the Miner produces chain errors in the logs.
What is the chain error? copy and paste the kernel log here.
This could a firmware issue, while T9, T9+, and S9 (all models except the k and SE) use the same control board, each has its own firmware, just like how T17, S17 and S17 pro use the same control board but you can't run a T17 with say the S17 pro firmware, I do not have T9 to test but I'd guess the same logic applies, so you need to get rid of that T9+ firmware using a Sdcard and then flash the T9 firmware ( I included all links in my previous post)