I Have a mikrotik haplite with the 6.44.3 firmware updated. I have plugged in a cable coming from the DATA IN of poe injector for my outdoor wifi repeater. Since I have plugged in the cable connected to the poe injector i thought there is a connection and they were communicating but as I plugged out the cable. theres the led light keeps on blinking.
I have tried to inspect if the port was dead using wireshark yet it still broadcast STP and as I turn on the loop protect. the port detected to have a loop.
I have also tried net install but it still light up the led.
Thank you very much in advance for helping me.

Closely inspect for any bent pins inside the connector. If you're not affraid of opening the case, inspect the circuit board for any traces of corrosion or impurities. Or some damages (cracks, shorts) in soldered parts ...

Closely inspect for any bent pins inside the connector. If you're not affraid of opening the case, inspect the circuit board for any traces of corrosion or impurities. Or some damages (cracks, shorts) in soldered parts ...

Can I resolder it again?

If you are experienced and know exactly what you are doing, sure. But I guess in such case, you wouldn't be asking. Also, keep in mind that soldering will certainly void any warranty on the product..

If your product is still under warranty and you don't see bent pins, I would recommend to contact your distributor and apply for warranty replacement/repair/return.
On the other hand, if it happened AFTER you connected a POE injector, I would be certainly curious if you didn't accidentally plugged in the DATA+POE cable from the injector. Passive injectors will push power through, no matter what is connected. And hAP lite obviously does not accept passive POE-IN on any ETH port - that might actually cause the failure.

Mine is doing the same thing. Hap Ac Lite. Nearly new, stable firmware, just sitting on top of my computer in a cool room.
I've reset, changed firmware, defaulted etc without luck.