I user bass B1 . I'want Downgrade T1 and power stand
L1 Model II Firmware version 1.1 is obsolete and not longer available.Even if you can find a copy of version 1.1, you should NOT install it.
The latest customer updateable version is 1.4. You can get it here.
Note: Version 1.4 fully supports the B1 as well as the B2.