In response to several incidents involving calculators getting bricked (permanently stopping working) in the last 6 weeks, HP has decided to remove the firmware from their FTP server and has put the previous version, 8151, back online:
ftp://ftp.hp.com/pub/calculators/Prime/
We hope that HP can release a fixed version of the firmware in the near future.
Source: https://tiplanet.org/forum/viewtopic.php?f=55&t=18294&start=50#p204122
It appears that the firmware is now back at ftp://ftp.hp.com/pub/calculators/Prime/Archive/ , but the main download link at ftp://ftp.hp.com/pub/calculators/Prime/ still has the old firmware. I guess many people requested that the new one be put back online, but it still appears, from the date, to be the same 10077 with the bricking issue.
So a new firmware, 10637, got leaked on HP FTP, but removed soon afterwards. Whether it fixes the issues in 10077 or not is unknown, same for the changelog. It was removed because it was not intended to be released this early:
ftp://ftp.hp.com/pub/calculators/Prime/
https://tiplanet.org/forum/viewtopic.php?f=69&t=18961&p=206772#p206751
http://www.hpmuseum.org/forum/thread-6776.html
As for the issue shown in the HP Museum topic, I had the same problem while transfering every past OS or so. The progress bar moves but transfer usually cuts off and fail at a random percentage and I had to try between 2 and 20 times before it finally reaches 100%. I have not tried installing the new firmware, though.