ARC-8050T3-16R unit can start up alone indicate the controller is normal, so the most possible problem is the connection between host and the controller: the thunderbolt daughter board or the cable. There has two kind of condition for the daughterboard one Thunderbolt standby state corrupted or without seating properly.

1. Execute a clean force power on to clean the Thunderbolt standby state. A clean force power on procedure is as below:

a. Disconnect power cable and thunderbolt cable from raid box

b. Unplug all drives in box

c. Connect the power cable, then press the reset button on back for few seconds to force power it on.

If the raid box starts up correctly, you can hold the reset button for few seconds to power it off, then connect drives and thunderbolt cable to see if it works now.

2. The problem comes from daughterboard not at accurate position or screw loosened. Follow the document to pull out the RAID controller and re-seat the daughterboard again.