These devices don’t have any kind of internal memory, everything is read from the sd card, so it is not possible to brick the device.
They also do need a working system on the memory card to charge properly.
You are most probably just stuck in fel mode, when the device is not properly shutdown and the sd card is removed.
Without a card press reset three times, insert a working card, hold the power button and while holding press reset 3 times, release the power button. Plug the device to charge and check its status then.