No hdmi signal after login

Hi, first post here. Im running Armbian 23.11.1 bookworm.on Le Potato
connected to 5v 4a power supply.
system boots to the GUI. I enter password hit return, screen goes blank, then mouse pointer disappears. the system is still running, i can SSH into it and install/update ,but the screen says NO SIGNAL…ive changed hdmi cables/ports no difference. Any Ideas what causes this?
Thank You

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