Dear supports.
After using a year, the modem became bad
When turned on, it does not see the modem.(QMI - /dev/cdc-wdm0 before)
So what’s now?
Before that, I did not disassemble the modem. 
Bad news…Modem not detected after new adapter QMI replacement 
The mainboard E750 has a problem with USB power. I didn’t close anything 5V…
I tested the USB-QMI adapter on a PC, it works, it will determine it in the device manager.
tried to change the OpenWRT firmware and stock without results
Then I’ll try to connect the HUAWEI USB modem, the same problem 
Posted the logs + screen.
logs.zip (571.5 KB)
Briefly there is a note error usb usb1-port1 and next… :
[ 8.841204] usb usb1-port1: Cannot enable. Maybe the USB cable is bad?
[ 8.966205] random: jshn: uninitialized urandom read (4 bytes read)
[ 9.103025] random: jshn: uninitialized urandom read (4 bytes read)
[ 9.141016] random: jshn: uninitialized urandom read (4 bytes read)
[ 9.797738] usb usb1-port1: Cannot enable. Maybe the USB cable is bad?
[ 9.804555] usb usb1-port1: attempt power cycle
[ 10.781737] usb usb1-port1: Cannot enable. Maybe the USB cable is bad?
[ 11.436002] eth0: link up (100Mbps/Full duplex)
[ 11.440765] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 11.685761] usb usb1-port1: Cannot enable. Maybe the USB cable is bad?
[ 11.692582] usb usb1-port1: unable to enumerate USB device
How is it possible to fix the main board problem?
Is there an E750 diagram for a service manual or repair? (important)
Is there sell replacement parts? (optional)
Thanks.