Mi 8 is now charging at very low rates

Phone is now charging at only 300 mAh. If I try to charge with phone switched off, a bootloop occurs. Also, phone is no longer being detected by PC (usb menu doesn’t shows up);

• Cables and charger - ok (tested with different ones);
• USB Port Board - replaced;
• Battery - replaced;
• Factory reset - done;
• Firmware reinstalled - done;

Any idea? Please!