Concept Board Jar Jad Sjam freeze | Telit Cinterion IoT Developer Community

Dears,

I try to install a jar/jad code on EHS6 modem.

Operations : 
1) Placing jar & jad using a:/module tool with USB cable
2) Installation with at^sjam=0,"a:/app.jad",""
3) Waiting and checking installed app with at^sjam=4

Firstly, working on EHS6T, everything is ok !!

Using the same jar/jad file on concept board, 1) is ok. On step 2) the command terminal freeze and no "ok" message appears, no more AT response, ... 30seconds later, I manually reboot and check installed app with step 3) but I only see jrc app...

Last, for our application I realized a complete PCB. USB connection OK, PSU ok, modem startup OK (Vcore 1,8V ok). 
Step 1) OK but again freezing on step 2).
I see on step 2) the consumption of the PCB goes from 0,4W to 0,6W during the 5 to 10 first seconds of freezing.

Maybe configuration problem (scfg ?) ?
Or an hardware limitation ?

Thanks for your help,