WD HD TV powers off when external USB HD connected

Hi - hope you can help

My WD TV HD powers off when I connect and external USB HD

I have been using this device for many years with no problem

recenlty added some new films to my HD and then conneted it to the WD TV HD, which would not power on.

I have tried the following

unplug external USB HD - powers on OK

just USB cable conneected  - powers on OK

remove some files from HD - powers OFF (pwr light flashing)

plug external USB HD with WD TV HD switched off - will not switch on

system reboot (hard - paper clip hole) - no luck

system reboot (soft - menu option in settings) - no luck

plug another external USB HD - powers OFF (pwr light flashing)

both USB sockets used - powers OFF (pwr light flashing)

Any suggestions or do i have to put in bin (sorry recycle) and buy a new one

thanks - virtual beer voucher or anyone with the solution

are these usb bus powered drives (aka self powered)  or externally powered hdds ?

have you tried just a simple usb flashdrive (thumbdrive) ? … just curious if it will do the same thing