how can i flash ACER Aspire 4752G BIOS?

Meeedo0o0o

Yes, I'm pressing the FN key at the same time.

JackE

No conclusions yet except that the keyboard is still suspect. With the HDD and RAM connected, and nothing else plugged into the external ports, (not even a mouse dongle), how long have you waited for the 75% screen to change? An hour? A few hours? Overnight?

Meeedo0o0o

Less than an hour. Around 15 minutes.

JackE

Please try it again plugged in for at least an hour, preferraby longer if possible. Your system is slow by today"s Win10 standards so it may need a lot more time to process changes made.

Meeedo0o0o

Do i need the windows 10 USB also connected? Or only the laptop HDD and RAM?

JackE

Only HDD, RAM & charger. Nothing else plugged in. Not even a mouse dongle.

Meeedo0o0o

I left it for 12 hours and the screen didn't change. 

JackE

Does your Windows installation USB pendrive have an LED activity light?

Meeedo0o0o

No, it doesn't. 

JackE

We need a USB pendrive with an activitiy light to test if the BIOS can even read a USB pendrive. If the BIOS can't respond to the pendrive, the BIOS chip can't be recovered except possibly by an eeprom programmer or replacing it with a pre-programmed chip. The latter two options aren't that expensive but require low-level programming or desoldering skills well beyond the capability of most of us on these user forums

Meeedo0o0o

I have a USB with activity light but it's not the windows installation USB cause it's capacity is only 4 GB. 

JackE

OK. Download & unzip this compressed file. Then look for a DOS subdirectlory in the unzipped file. Copy the JE40219.wph to the root directory of the 4GB USB dirve that is FAT32 formatted. Insert the USB drive into the turned off machine with the charger plugged in. Then press and hold the FN+ESC keys. Turn the machine on  and watch for LED on the USB drive. If LED activity shows, release the FN+ESC keys and see if the LED activity continues. Let it continue till it stops or the machine shuts off.

Meeedo0o0o

I followed all the instructions. The USB light flashes for 2-3 seconds and stops then flashes for 2-3 seconds and stops then again the same for four times in total. Everytime the HDD light on the laptop also flashes once only before the USB light flash. The DVD player made sound once at the start. I left the laptop for 1 hour and it didn't shut down. I forced shut down and started and same screen with ACER logo and 75% BIOS.

JackE

Rename the JE40219.wph on the FAT32 4GB pendrive to BIOS.wph and try the same thing again.

Meeedo0o0o

Same results.

JackE

>>>The USB light flashes for 2-3 seconds and stops then flashes for 2-3 seconds and stops then again the same for four times in total.>>>

Does the same thing happen when you turn the machine on but NOT pressing & holding FN+ESC?

Meeedo0o0o

If I don't hold FN+ESC, the USB flashes for 2-3 seconds one time only then the screen stops at ACER logo and 75% BIOS loading.

JackE

Good. That likely means the BIOS is trying to read the USB file when you press FN+ESC. The problem FN+ESC method for flashing the older Phoenix BIOS outside Windows or DOS is not well documented. So we have to experiment.  Try renaming JE40219.wph to JE40219.fd. Then do the FN+ESC method again. Please keep track of what you try so we don't repeat ourselves.

Meeedo0o0o

Same results with JE40219.fd
How long you think I should leave the laptop before I force shut down everytime i try this method?
I have the battery connected everytime i try this method.
Shall the USB light stay on for sometime to indicate some process is happening after the flashing?

JackE

>>>Shall the USB light stay on for sometime to indicate some process is happening after the flashing? >>>

Yes, the USB LED should show continued activity for about 5 minutes. If successful, the activity should stop and the machine should automatically shut down after about 10 minutes.

Some Phoenix BIOS chips can't read or use either of the two JE40219 files to flash itself with FN+ESC method unless the USB pendrive is made bootable with a small DOS-like environment called MiniDos that loads on the BIOS chip before the stuck 75% screen appears. To make it MiniDos bootable, you must do a google internet search for a file MiniDos.sys that is copied to the pendrive along with the JE40219.wph & pflash.exe.