I was given a 2014 I5 13" MBA (1.4ghz, 4gb). It had been dropped. I fixed the hinges, replaced the display with a good used. No Backlight with the new screen, but display works. Blown fuse for backlight driver on the logic board. I got it working just fine with external monitor. Replacement LCD Display works, I can see the display with a flashlight. Rather than repair the backlight driver (I'm and EE with experience at repair), I bought a NOS "late 2013" logic board, which was tested good in all respects from an Ebay seller with good reviews. I successfully upgraded the High Sierra to Big Sur while waiting for the NOS logic board. Again, machine worked fine in all respects. I replaced the logic board. No boot. The charger works. The fan works. Just no boot or any other response. I tried the NV and SCM resets. I got a response by looking at the charge light go from green to yellow to green. I've tried all the safe mode boots. I made a High Sierra USB boot drive thinking I could do a Option + Power boot drive startup and hope that the firmware would be updated. No response.
I've read that my 2013/2014 NOS logic board probably has 2013 firmware on it which won't see the APFS drive (I changed SSD format from HPS+ to APFS when I went to Big Sur).
I put my old board back in and it works as before. Put the new board in and nothing. The board was well packed in a static bag and padded box. I was very careful about the cable disconnect/connect. Of course, I had to swap the RF board and the SSD between boards.
The NOS replacement board is slightly different. It has the same board number: 820-3437-B but has a 1.3ghz CPU and 8gb RAM v.s. my original 1.4ghz CPU and 4gb RAM. I was told it would drop right in and work (except maybe for the firmware issue). But that the machine would at least boot so I could revert back to High Sierra, update the firmware, and re-upgrade.
So that's my question. Is the board just wrong? Did it get damaged? Is the Firmware difference a possible problem? Should I get at least a boot response? I get absolutely NO response from the computer other than the fan turns on.
Ideas? I know the machine is 11 years old. I have a very specific ham radio project I want this machine for. It functions perfectly otherwise. Plus I'm kinda enjoying the diagnostics and repair process (I retired last year).
I've read that my 2013/2014 NOS logic board probably has 2013 firmware on it which won't see the APFS drive (I changed SSD format from HPS+ to APFS when I went to Big Sur).
I put my old board back in and it works as before. Put the new board in and nothing. The board was well packed in a static bag and padded box. I was very careful about the cable disconnect/connect. Of course, I had to swap the RF board and the SSD between boards.
The NOS replacement board is slightly different. It has the same board number: 820-3437-B but has a 1.3ghz CPU and 8gb RAM v.s. my original 1.4ghz CPU and 4gb RAM. I was told it would drop right in and work (except maybe for the firmware issue). But that the machine would at least boot so I could revert back to High Sierra, update the firmware, and re-upgrade.
So that's my question. Is the board just wrong? Did it get damaged? Is the Firmware difference a possible problem? Should I get at least a boot response? I get absolutely NO response from the computer other than the fan turns on.
Ideas? I know the machine is 11 years old. I have a very specific ham radio project I want this machine for. It functions perfectly otherwise. Plus I'm kinda enjoying the diagnostics and repair process (I retired last year).
