Hi,

Is good to hear that a corrupted kernel can't brick the 770.
OTOH it is always good to be able to do a complete restauration of a device without sending it back to the vendor.
So I'm still curious if the connector is a RS232, TTL or a JTAG port.

Well, the X-Loader could be low level loader which ist written using the JTAG port (IF the connector on the back is indeed a JTAG port).
NOLO would be the USB-capable NOkia LOader, but that is the simpliest thing to guess