Sometime, the thin clients can not bootup or dosen't work, we can try to recovery it's firmware.
There are two ways to recover firmware (for J35N, J70, J90, J90D...) :
1, Factory Reset: There are two mirror file systems on the board. Factory reset means to restore the OS from the backup filesystem.
(1). Connect the thin client to the monitor, keyboard and mouse.
(2). Connect the thin client to the power adapter.
(3). Press and hold the power button for 15 seconds.
(4). When the monitor shows "Factory reset" and "Reboot" options, then release the power button.
(5). Use the up and down keys to select "Factory reset", it will take 5 to 10 minutes to recover the firmware, and will automatically shutdown.
(6). Then trun on and turn off the thin client twice, it should work well.
2, Firmware Update: this way will update the firmware directly in eMMC storage, if fail by this way, generally it means the hardware failure or the power adpater failure.
(1). Download the firmware and update tools from JIEYUN ftp server: Download Link.
(2). Follow the FW-Update-Manual.pdf to update the firmware
(3). When update successfully, please trun on and turn off the thin client twice, it should work well.
You can try other USB ports of PC or another PC, Win7 is recommended.
Devices Manager will decover the device
Updating the firmware