MacBook Pro A1990 Question mark folder repair

Problem description
Question mark folder, no external boot possible & Recovery does not work on A1990 MacBook

Symptoms

 * Question mark folder
 * No external boot possible
 * Recovery does not work

Solution
- Check U9080, U9580, U9000 & U9500 and SSD power rails PP2V5_NAND_SSD0, PP2V5_NAND_SSD1, PP0V9_SSD0, PP0V9_SSD1, PP1V8_SSD0, PP1V8_SSD1

- Flash T2, Update Intel Mac T2 BridgeOS Firmware, Boot Mac into DFU Mode Then Reinstall MacOS Via Recovery CMD R