Comcast Firmware upgrade on SB5100

Unplug the modem from the power. Wait at least 30 seconds. Plug it back in. If the correct version of the firmware is not present, it will automatically be pushed out at that time.

When you say "The old firmware, which allowed control of the SB5100", I'm wondering what control you had. The only control that should be available to you is to reset the modem. If you had more control than that, you probably had the wrong firmware, and the correct version was pushed-out the first time you power-cycled the modem.

It looks like you do have the latest firmware onboard. My 5100 is only about a month old and is running the SB5100-2.3.1.3-SCM00-NOSH version which appears to be earlier than your version. I think the 2.3.1.6 is the latest from Morotola but some markets have not pushed it yet.

SB5100-2.3.1.6-SCM06-NOSH is the farley latest production firmware for the SB5100. The NOSH means "no shell". It also means no entry. There is no way you had control over the SB5100 unless you had SB5100-2.3.1.3-SCM00-SH "shell version" and had an orange SB5100 with a special connection on the back of it that looked like a 1/8 stereo connection.You also needed a 9-pin serial to 1/8 connector cable. There were some older revisions of code that allowed some basic functions that the newer revision stripped away.

The only way to get the SB5100-2.3.1.3-SCM00-SH back it to have them do a firmware push from SNMP back to your modem. Simply unplugging your modem and plugging it back in will not restore your old firmware since a mass upgrade was performed most likely. In reality you are not asking Comcast for a firmware upgrade but a downgrade.