Talich and Michael - Thanks once again both of you for your patience with this old fart. I was able to do as you said Talich although the Odin window said fail. It will now boot normally when disconnected from the power supply.The device with this screen is in the Downloading firmware mode and it is waiting for uploading files via ODIN, so nothing changes
You need to flash the stock firmware T290XXU3CVG3 or at least the stock kernel and vbmeta. I will attach the file with them, try to flash it first by selecting the AP window. If the problem persists, then flash the full firmware T290XXU3CVG3.
With my new root status I was finally able to modify the playlpm file and now when the usb power supply is connected it starts to boot but now it gets stuck on this screen attached and won't go any further. I have to manually press the power button until it shuts down, disconnect from the psu and then press the power button again before it will boot normally. This is the playlpm file I placed in /system/bin:
Any ideas? Thanks Tony.