The hashboards are sockets are labeled on the control board, just follow the ribbon cable from the hashboard to the control board and you will see each has a number, ignore the number as it's sometimes different on the 17 series but focus order, for an example if you have J4, J5, J6 on the control board, and 1,2,3 on the miner status page, J4 will 1, J5 will be 2 and J6 will be 3.
To double-check you can just unplug the cable that goes to the board and then power the miner on to check for any changes.
Yes, the kernel log has some useful info in it. You should never buy mining gears off Alibaba and Aliexpres.