In the case of a custom carrier board you do have to have the board support package content in place prior to flash. This is mainly device tree, and will pass arguments to drivers about hardware layout. Without this the drivers can’t find the hardware.
Bluetooth may have similar issues if the method of connecting the bluetooth uses an interface which required a firmware change for the non-dev carrier board.
The definitive method of determining how boot works is from serial console, but once again, the serial ports will not function correctly if the device tree is not correct. Serial console might work if that part of the layout of the alternate carrier board is the same. Basically, you might need to test. However, if you didn’t have the correct firmware updates in place prior to flash, then you will very likely need to reflash. So that becomes the big question: Did you have the correct J90 BSP files in place prior to flash?
In terms of ethernet, I don’t know if the wiring you used is correct or not. It sounds like it would be correct if the other end is a switch, but perhaps your situation would want a crossover cable configuration instead. In the case of crossover, sometimes an ethernet PHY will understand this and automatically detect and change to crossover. I have no idea in your case what would happen.
If you have the BSP in place, then I would start with serial console. The connector would differ from the devel carrier board, but the rest of this information would be valid (and the J90 documents should give serial console information as well):
If you do flash, then the logs would help. If you hover your mouse over the quote icon in the upper right of an existing post, then other icons will show up. The paper clip icon is for attaching files. You can adapt this for your case, but if you were to flash on command line (and I don’t know what changes the J90 flash would require), then you would add something like " 2>&1 | tee log_flash.txt" to get a log. For example:
sudo ./flash.sh jetson-tx2 mmcblk0p1 2>&1 | tee log_flash.txt
Btw, if you have a serial console log (and minicom and other serial console software can log), then paste that in as well. It might mean successful flash, but we’d have to examine the log.