Just a reference: if the down unit is A and the B unit is working. Put the A unit on the B terminals to eliminate your outdoor unit as the problem. Then you'll need to ohm your wires to be sure all wires are good. Then you'll likely just need a board for indoor unit, not much else left. If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79
The indoor EEPROM unit
1 ChecK whether there are false weld or bad connection etc, between the EEPROM chip block and electronic control board,
2 check whether the EEprom chip is broken foot and the direction of the installation is in line with EEPROM block.
3 When the procedure of EEPROM chip and itself have fault the code FH will appear. That is a need to replace EEPROM chip.
If you don't evacuate the system/vacuum you will be contaminating the refrigerant. Reduced efficiency and premature compressor failure are destined to be in your future. You must at least purge lines. Hope you're confident in your flares/solder joints. Does the condenser come precharged? There has got to be a service valve or you cut them off to not have to flare. Good luck If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79