Edgar

Dear Armbian Community!
I've run into the same issue and this thread put me on the right track. I've managed to resolve it meanwhile and I want to share my case with you here.
 
I've used my Odroid HC4 with one Toshiba 14 TB harddrive for a while without any issues (> 1 year).
Recently I purchased a Thoshiba 16 TB HDD and replaced the 14 TB with it. It run a couple of days without an issue. Then, after I updated and rebooted my Nextcloud Pi installation, the drive was not recognized anymore. I cannot remember the exact order of my subsequent steps, but since I own a 2nd HC4 hardware, I once swaped the slots, another time the whole HC4. After that I ended with on dead drive slot on one, and with two dead slots on the other HC4.
 
I downloaded the schematics and measured the output test points of the switching regulator circuits. At each defective drive slot 0V were present at the output of the regulator circuit. Therefore I concluded defective DC-DC converter ICs as well (my current guess is, that the larger Toshiba drives, namely the 16 and 18 TB ones have some sort of higher inrush current at spin up / system reboot. Maybe out of SATA spec, or maybe the HC4's regulators are just a little too weakly dimensioned)
 
I looked for a fully compatible converter IC, but with better specs. And fortunately I've found one. Altough with the same max current of 2 amps, but with a mentioned 2.5 amps peak current rating. And the max input voltage is higher as well - 24V vs. 18V.
This tells the professional or the ambitious hobbyist that a stronger switching FET is integrated in this IC.
 
I ordered them here https://www.mouser.com/ProductDetail/DIOO-Microcircuits/DIO6912ST6?qs=%2BEew9%2B0nqrDv2h%2BRFnw9pw%3D%3D and replaced both in each of my HC4s. It's been working for a few days now with the same 16 TB Toshiba hard drive. Hopefully for a long time.
 
(2 photos attached - 1st shows the desoldered converter ICs U24,U21, 2nd the new soldered ICs - you have to be very careful not to accidentally unsolder the tiny passive components very close by)