So I set up a SixXS IPv6 tunnel endpoint on the WRAP, and while reading the OpenWRT documentation, I stumbled over the mentioning of LEDs. Turns out that OpenWRT can trigger some boards’ LEDs on a number of events - which let me configure two special purpose LEDs instead of the two unused-by-default in the WRAP’s array of 3 GPIO LEDs.
Got a WD MyBook Live NAS with a broken NAS circuit board? Want to
rescue your data off the standard 3.5” SATA disk inside the NAS
enclosure? Tried mounting the block device on your Linux system and
just got the kernel saying
EXT4-fs (sdg4): bad block size 65536?
This article summarizes what I had to find out while I was in that situation.