Cannot properly power LEDs
as you mention these boards are from Headlamps, with LED board did you find another board inside the headlamp?. because the board you are missing is LDM (LED Drive Modules). This is a self-contained power supply, that accommodates the LED’s powers. The modules have multiple channels to provide varying currents to different LED’s. These modules are used to power LED’s which are used to customize to accommodate the LED’s it powers. if you have that board, then you just connect the board with the LDM and give power to the LDM between 9V to 16V as it is headlamp it can take up to 6Amp of current approx, and check the results. if you didn't find the board don't worry, but you can still turn on these LEDs but not recommended. use the power supply in CC mode to drive the LED board.in my case, what I have done, I'll explain in brief, I have APlab 30V10Amp variable power supply, connected the LED board to power supply and I keep the current knob to 0 and start increasing voltage knob to around 6 volts as I increase the voltage PS goes into the CC mode then I started increasing the current the LED start glowing. it worked for me maybe it will work with you.
note:- do not run the LED for more than 10 sec. they are high power LED and without proper heat management the led may damage.