I have ruined attiny2313 trying to burn "tinycore" to it.
i spend couple of days to get it back online again.
Only solution i found was to use originala stk500 to set fuses again, i tried various methods ..
I use following site to ensure correct fuse values.
This method how to wire stk500
Parallel High-Voltage programming.
Connect PROG CTRL header to PORTD and PROG DATA to PORTB as shown in the figure in section "Parallell High-Voltage Programming"
and finally this string to erase chip (attiny2313 with 4Mhz crytall)
sudo avrdude -c stk500pp -p t2313 -P /dev/ttyUSB0 -e -U lfuse:w:0x6c:m -U hfuse:w:0xdf:m -U efuse:w:0xfe:m -B250