Is there a way to recover a modem for which the firmware update was interrupted?
I interrupted the firmware update and the last thing the modem said was “ERROR IN DECOMPRESSION” and “UNRECOGNISED FILE”. Now it doesn’t start or respond to any AT commands 
I was using Hyperterminal to manually update the bootloader and firmware because DS has been throwing all sorts of cryptic errors - which it tends to do if you don’t have the correctly matched versions with binaries.
What modem is it? You can normally put the modem into boot mode using the boot pin and use DWLWin to download new firmware.
Its an SL6087.
I’ll give that a try and report back.
To expand on the question; why would the modem partially install its firmware? Shoudln’t it verify the entire download before corrupting the existing firmware, and does this imply the firmware update is risky?
Yes, I was able to recover this modem using DWLWin. 
The process was not nearly as easy as it could have been, given better documentation and access to software resources, so I’ll do Sierra’s job and add instructions here:
Download and Install DWLWin; requires login to SiWi developer resources (unnecessary but straightforward). The user manual is rubbish for ad-hoc usage, detailing loads of COM automation but not the actual physical usage.
Setup switch on BOOT pin of modem, in the SL6087 case its direct to the 1.8V pin
Get appropriate .wpk package for the firmware version. Once again, SiWi stand in the way by not publishing these conveniently. You have to do a request through the distributor, which is a massive waste of time. DWLWin only works on .wpK packages, not .dwl files, which is the only useful comment in the manual.
The package will include all firmware and bootloader as required - its quite neatly automated.
Start DWLWin and point it to your package(s); they should appear in the UI and you can select the one you want. Set for autodetect of module type. Press the START button
While its trying to detect the module, ensure the BOOT switch is on and reset (or power up) the modem. It will be found by the DWLWin software and some fairly straightforward questions will be asked on the way to reflashing your modem.
Works really well when you have what you need and know what to do. 8)
Where do you find these .wpk packages?
Hiya,
as richardw says:
(my emphasis).
The wpk files used to be available on the developer download area too - but they seem to have gone away now. Sigh.
ciao, Dave
I have noticed that (some) .dwl and .wpb files are the same, except the .dwl file has 160 extra bytes at the beginning, when produced by a build.
.dwl files just contains extra data to allow (1K-)X-Modem upload to the modules with AT+WDWL.
However .wpb files are not the same as the .wpk files.
IIRC .wpk files are zip-files that contain a lot more.
Yes, you are correct, the .wpk file can be renamed .zip and opened. It reveals an archive of various files, including some .wpb and .e2p ones.
I have also noticed some .dwl files contain several files, typically COMP .wpb and E2PR .e2p, however the the e2p text files have been compressed and are not easily extracted.
It seems likely, it would be reasonably simple for Sierra to convert .dwl to .wpk, except the filenames do not seem to be provided (or are compressed).