I've now also been able to fix the firmware upgrade process for new firmware versions.

It turns out that the pebble times out if it isn't sent a message quickly enough during the firmware upgrade process, and because the N9 isn't the beefiest of machines it takes too long calculating checksums on the new larger firmware files. So I've modified libpebble to do all CRC calculations prior to initiating the firmware upgrade and now my pebble is happily running firmware 1.12.1 .