Dell Inspiron 660 Bios Failire

power off during bios flash will brick the motherboard. 

Sorry, I don't understand... If you already had BIOS A13, why did you try to install BIOS A09?  That's a downgrade, not an upgrade. 

Where did you get BIOS A09? It's not currently offered on Dell's support page for Inspiron 660. A13 is the latest version, and A12 and A11 are the only prior versions offered.

Try clearing BIOS...

1. Power off, unplug power cord from rear of PC
2. Press/hold power button for ~15 sec
3. Open case and remove motherboard battery (check Service Manual for details)
4. Press/hold power button for ~30 sec
5. Install fresh battery, likely a CR2032 3-volt coin cell (~$3)
6. Close up and connect mouse, monitor and keyboard
7. See if it boots now

If that doesn't help, you can try doing a BIOS Recovery.  Download the BIOS A13 .exe file and save it on an empty (non-bootable) USB stick, that's not larger than 8 GB, and formatted FAT32. Now change the name of the file on the USB stick to BIOS_IMG.rcv  

After you rename the file on the USB stick, plug it into the Inspiron 660 with power fully off. Then power on and press/hold Ctrl+Esc when you see the Dell splash screen and follow the instructions carefully on the BIOS Recovery page (linked above).

"I used the official Dell .exe to upgrade to bios version A13 from A09 from within Windows 10"

Thanks for the advice, I shall give it a try. I'm not sure if the BIOS recovery is going to work since I don't make it to the DELL splash screen before the computer powers off and cycles on again, but worth a try.

@redxps630​ that would be very frustrating... I followed the Dell procedure and used the official Dell tool to do it... The process just froze the computer, couldn't move the mouse etc. Left it for 30 minutes in case it would come back, but no, had to restart machine and now dead...

Unfortunately I doubt Inspiron 660 supports bios recovery 1.  This is a 2012 Intel 3rd gen pc.  It is not listed as a model that supports Dell bios recovery.

”If your Dell computer shipped before December 2015 and is listed below, then it supports BIOS Recovery 1.”

https://www.dell.com/support/kbdoc/en-us/000132453/how-to-recover-the-bios-on-a-dell-computer-or-tablet

flash bios is inherently risky especially with older motherboard which may have brittle cmos chip.  Two options: time to move on to newer Intel motherboard. For example Inspiron 3847 mobo is Intel 4th gen and can fit 660 case.  Or buy a replacement 660 board, not recommended given age.  Finally if you are handy you can use a usb SPI flash tool to write a 660 bios dump file on the chip, but that needs investment of a tool and takes advanced skill not for ordinary users.

Thanks, appreciate your reply and advice. Replacing the motherboard with an Inspiron 3847 mobo is an interesting (and economical) idea. I will research this further, but do you think is would be a fairly straightforward replacement exercise in terms of compatibility with the case hardward, i.e. power supply and case headers would be a simple unplug and then replug and play in new motherboard? Looks like it's a socket 1150 so can upgrade the CPU at the same time, am thinking a i7-4790K if I can source one cheaply.

@redxps630​ thanks for the advice and insight, appreciated. The idea of using an Inspiron 3847 motherboard as a replacement is an interesting one, as it's probably time to upgrade and this is one such path. I will research it further, but would you know straightforward this swap would be in the same case e.g. would the PSU and case hardware headers simply unplug from the old one into the new one? I'd need to upgrade the CPU as well since it's a LGA 1150 socket, would probably try and find an Intel Core i7 (4th Gen) 4790 if I can get it cheap.

I had both pc. the case is compatible. You can use same psu and ddr3 ram. 

3847 board has an odd, strange, weird front panel Dell design: two pins of front panel header pins need to be jumped to work.  If you go down that route I can help in more details. I installed a 3847 board in a non Dell gaming case and used a small mod of 9 pin to make it work

https://www.dell.com/community/en/conversations/inspiron-desktops/3847-case-swap-dell-proprietary-front-panel/64d49530b52334366781cc0a?keyword=3847

@redxps630​ thanks for the kind advice, I might take you up on that offer!

Even if it was the Dell A09 BIOS .exe file, why did you try to downgrade?  Many PC models don't allow BIOS downgrading. 

Did you try clearing BIOS and replacing the battery?  And it can't hurt trying a BIOS Recovery. Power on and immediately press/hold Ctrl-Esc...

another Dell mATX motherboard that would work w 660 case is XPS8700 which is also Intel 4th gen and uses standard 9 pin FIO.  it would be a direct drop in.  can use same CPU cooler.  advantage of 8700 is a better Z chipset as well as 4 DIMM slots.  3847 has two DIMM and H chipset.

@RoHe​ 

"I used the official Dell .exe to upgrade to bios version A13 from A09 from within Windows 10"

You read it backwards.  I almost did at first as well.

I don't mean to change your BIOS update topic, but if you are thinking about sourcing motherboard and processor, that is not a good economic feasible upgrade plan as it may involve other associate cost.

Why not upgrade to a newer machine.  With a hundred-ish USD, you can get a whole system with 6th or 7th generation i7 processor, memory, operating system. 

if OP is interested to go on DDR4 platform, it is better to choose Intel 8th gen cpu which is a game changer from 6/7.  imo 6/7 are not much faster than 4th, except that ddr4 memory are faster and the cpu are more energy efficient.  the newer mobo do support M.2 ssd which is nice.  XPS 8700 has on board mSATA while 3847 does not.