Stm32 nucleo-f412zg powered externally acts weird

[PMoop.1]

I'm using Stm32f4 nucleo-f412z g for a test fixture kind of setup. After loading the firmware I want to keep the eval board in a box and power it externally with a power brick and usb. But when I do this, it doesn't work with the firmware I uploaded. It behaves weird, has anyone come across a similar issue or is there a solution for this??

[Ozone]

Check your "power brick" output.

Some have rather high voltages without load.

And others collpase near the current limit.

[PMoop.1]

Connected to a power supply, brought down input voltage to 3V, there's no difference. It draws around 60mA of current. @Ozone​ 

[Ozone]

Well, 60mA doesn't sound too much.

I once had a board with a LCD display that behaved strangely when powered by the integrated debug pod via USB.

Only with an external power supply it worked correctly.

I would still check the idle voltage of your power brick, and the temperature of all reachable chips at least with your fingers.

And try debugging.

Either an unreliable initialisation (clock/Flash settings). Or, if you loose the debugging connection at a consistent location, related to some peripheral.