Here is the answer
each "J" here represents a hash board which the control expects to find, your miner has 3 hash boards and so it expects to see J6,J7, and J8, but it can only see J6, in other words the other two chains/hash boards are bad/don't work.
it's also the reason why in this image which you posted
only 1 hash board has a LED on.
so first thing first, it's safe to assume that chances are, the seller just gave you a gear that hashes at 1/3 of it's hashrate and you have to live with it or return it if possible, however, the cause of this could be something else which you can fix, so you need to do a bit of troubleshooting, start with swapping the wires between J6 ot J7 and this includes all 3 PSU cables and the thin ribbon cable, do this, power the miner on and post the kernel log again.
Code:
driver-btm-c5.c:13421:bitmain_c5_init: Chain[J6] has 63 asic
driver-btm-c5.c:13449:bitmain_c5_init: retry Chain[J7] has 0 asic
driver-btm-c5.c:13449:bitmain_c5_init: retry Chain[J8] has 0 asic
driver-btm-c5.c:13449:bitmain_c5_init: retry Chain[J7] has 0 asic
driver-btm-c5.c:13449:bitmain_c5_init: retry Chain[J8] has 0 asic
each "J" here represents a hash board which the control expects to find, your miner has 3 hash boards and so it expects to see J6,J7, and J8, but it can only see J6, in other words the other two chains/hash boards are bad/don't work.
it's also the reason why in this image which you posted
only 1 hash board has a LED on.
so first thing first, it's safe to assume that chances are, the seller just gave you a gear that hashes at 1/3 of it's hashrate and you have to live with it or return it if possible, however, the cause of this could be something else which you can fix, so you need to do a bit of troubleshooting, start with swapping the wires between J6 ot J7 and this includes all 3 PSU cables and the thin ribbon cable, do this, power the miner on and post the kernel log again.