HI, Ive been happily updating my Ender 3 fitted with 4.2.7 board now and again with new builds. Last two times the update bricks the printer and I had to go back to one from June 22 using the trick with “firmware_update.bin”.
Is anyone else having this problem? The filename trick no longer works.
Is anyone else having this issue - I have it every time now 
Have you tried reformatting your SD Card?
The most common cause of failed flashes are SD card problems.
I just spent a few minutes trying some new cards and it seems that using a completely empty card works. I guess you could format it to be sure each time. I was previously trying with cards that had BIN and EEPROM.DAT on them still and I reckon that was causing some issue.
Although I had been updating just on the same card as my print files for some time - this may be some issue in the firmware that has crept in in recent versions?
Unlikely to be the firmware - as the flashing is handled by the bootloader - so its before any real firmware loads…
Perhaps post upgrade and first boot its getting confused somehow and failing to start - I just get a blank screen.