OK, let’s see:
Past Step 1: Cheap digital multimeters usually come with slow analog-digital converters, therefore “little change” is a strong indicator for the problem. Addionally, it is highly likely that the bed connector suffered from mechanical impact if the connection cover has been loose.
Open the bed connection cover, remove the hard silicone carefully using tweezers or long-nose pliers & re-solder the contacts. Install the cover. Re-run bed PID-tuning. After the problem should be solved finally.
There is no reason to worry about anything: You did not mention which firmware is currently installed on your SV04 - I suppose it is the stock firmware. Judging by source code available Sovol did not put much effort in their firmware to support SV04 host operation. There are known host report issues which have been fixed in custom firmware versions. You may want to read this before changing the firmware.