HP ProBook 640 G2 not booting when HP LT4120T WWAN card is installed into motherboard

[TonyWasiele]

Hi, I have an HP ProBook 640 G2 laptop with 8 gigabytes of ram and 500 gigabytes of storage. It didn't come with a WWAN module but it has antennas. I installed WWAN module HP LT4120 which should be compatible. The laptop works perfectly fine without the module but as soon as the module is installed to its designated M.2 slot, the power button doesn't power the laptop on and the capslock button blinks long (white). If I remove the module the power button (and the laptop) works perfectly like before. I have done testing and narrowed it down that it is enough that the LT4120 module is installed, it doesn't matter whether the antennas are connected or not.

I did at one point have to disconnect the CMOS battery to reset the BIOS due to it not starting... It seem to do the trick as long as the lt4120 was not installed

Could this be issue with UEFI settings or what could be cause for this?

[pepe999]

Hi,

This computer supports only three WWAN modules:

Foxconn Amstel LTE/EVDO/HSPA+ w/GPS M.2  822828-001
T77W595 LTE M.2 w/GPS                                        800870-001
Huawei Wrangler MU736 HSPA+ w/GPS M.2     793516-001

The system won't boot unless there is one of those three modules installed. 

[TonyWasiele]

When the WWAN card is installed, the computer does not boot....  yet I have the correct WWAN card... But it does go inside upside down with the antenna connections facing up towards the screen... Is this correct?

[TonyWasiele]

I have two different WWAN cards but they both have the same effect. It will not boot and the caps lock key blinks long white and keeps blinking like that until the WWAN card is removed from the motherboard. Am I using the wrong cards?