I connect the serial port to gain access to uboot, then the battery leds start blinking and the device doesn’t start
Only start when connect the power from the serial to the serial pin in the board.
The four battery leds blink three times.
I bricked de device???
Can you repeat your question?
When the led blinks when not blinks.
Blinks means that battery power is low.
the leds are always blinking and the device doesn’t boot
But you said it start when connect power? Can you describe in more detail? What is the relation with serial port?