Instead of six separate images for the left end, right end, and tiled
center portion of the full and empty progress bars, just use two
images: a full bar and an empty bar. Draw the left side of the full
bar and the right side of the empty one, moving the boundary rightward
to "fill" the bar. This makes recovery trivially smaller, and allows
fancier images to be used as progress bars.
Support paletted PNG images as resources.
Take some device-specific details of the recovery UI (eg, what keys to
press to bring up the interface and perform actions, exact text of the
menu, etc.) and split them out into separate C functions. Arrange to
take implementations of those functions from the appropriate vendor
directory at build time. Provide a default implementation in case no
vendor-specific one is available.
