My Zyxel AP does not boot. The Power LED is on but all other LEDs stay off. If i connect a Ethernet cable to the unit a computer recognizes the Ethernet link but the corresponding LED on the AP does not lit up and i can't communicate by TCP/IP with the AP. I also noted that the CPU of the AP gets slightly warm. If i connect to the AP with UART, all i get is:

U-Boot 1.1.3 (May 19 2009 - 10:05:30)

Board: Ralink APSoC DRAM:  64 kB
relocate_code Pointer at: 7ffb4000

For me it looks like the boot loader does not even run properly.

Is there a way to reinstall U-Boot?

Thanks for any help.