check your hardware, check the USB cable, consider using original power source, change the USB port
start again the node and try to bring up the debug logs for a better understanding of what is going on. Post the link (only) to the logs, it will generate automatically a link and you will find it at the end of the log.
you could try reflashing the mSD with the latest version of Umbrel (now is 0.4.2) and start again your node.