A brief yellow LED during transmission signals an invalid received packet
sequence number (which means network packet loss).
Modem trying to transmit, but an active BCLO is preventing it:
Modem transmitting, packet with invalid sequence number received
(indicating packet loss):
Modem receiving:
Hardware error:
If you see this LED state then please refer to the troubleshooting section for
help.
Power LED
The power LED is steady yellow when the device is charging the battery.
Battery overheat error is indicated by slow yellow blinking. Other charge errors
are indicated by fast yellow blinking. Please refer to the troubleshooting section
for help in these cases.