I am trying to build a digital watch.I intend to use the 32 kHz crystal for timer2 in async mode. I know I should have used a 328P instead of a regular 328 but I didn't have one on hand and buying stuff during the coronavirus is difficult. So I decided to go with the 328 for prototyping. I am using an Arduino Uno board as ISP. I loaded the Pro mini 8Mhz bootloader on it and it worked fine. Then I moved ahead with changing the fuse bits. I set the fuse bits to HIGH : 0xDA LOW: 0xE2 Extended: 0xFF. After changing the fuse bits I rechecked the chip using avrdude command and it had the desired fuse bits. The chip previously had a Blink sketch prior to change the fuse bits and it was working fine. But when I tried to upload another program using Arduino IDE i got the avrdude : device signature : 0x000000 error. The blink sketch had also been erased. Afterwards when I rechecked using command line it showed the same error message and then showed that the fuse bits were all 0x00.
I have tried :-
Using a different power supply other than the Uno.
changing the clock crystal
Lowering the baud rates
Attaching decoupling caps on power pins and loading caps on the crystal pins (although for a 32 KHz, I am told that these are not necessary)
Avrdude also gives the error message programmer not responding whenever any other command is passed.
I can confirm that there is a bootloader on the chip as any LED connected from SCK pin to ground will flash whenever I reset the chip.
I have to tell this beforehand:** I do not have an oscilloscope & I do not have any other ISP**.