lb2120 orange light no 4g connection

[super_gromit]

i have a lb2120 that i have been using as a fall over wan connection on my pfsense router for over a year and it has worked perfectly up until a day ago when it dropped the mobile connection and now the power light remains orange. i have tried a factory reset, using a different sim card and checking for updates and none are found. this seems like a common problem with them just failing like this with no real resolution to the problem. are there any tricks or tips to try and revive it