My phone went off problem with battery not showing amp

My phone went off when I restarted it at 8% battery and was still plugged into the charger. I went to Samsung authorized center for a fix. They told me that the battery wasn’t showing the 1.2 amp power on their device and it’s not booting up. I asked them to replace the battery or check the charging port they keep saying that it’s not the issue. Is there a possibility to get it turned back on because they said if it won’t work then the whole motherboard is required to be changed. Also, he said that he will try with a wireless charger to see if it helps in powering up but my phone isn’t wireless charging capable.