DIAGNOSIS The router has a corrupted firmware or boot loader. A solid amber power light indicates a failed boot process. It is partially bricked.
FIX You must perform a TFTP recovery. Download the latest RAX50 firmware .img file from Netgear's website to a computer. Connect that computer via Ethernet to one of the router's gray LAN ports. Set the computer's IP to 192.168.1.10. With the router OFF, hold its reset button with a paperclip. While holding reset, power the router on. Release reset when the power light blinks amber. Now run a TFTP client on your computer and push the firmware file to 192.168.1.1.
IF THAT DIDN'T WORK The hardware may have failed. As a last resort, try a 30-30-30 reset. With router on, hold reset for 30 seconds. Keep holding while unplugging power for 30 seconds. Still holding, plug power back in for 30 seconds. Release. This is a full NVRAM clear.
HEADS UP Never interrupt a firmware update. A power loss during an update is the most common cause of this amber light. Always update firmware wired, not over WiFi, and ensure stable power. Use a UPS if possible.