Here's a completely rewritten "Arduino as ISP" sketch that can program the ATtiny85, in situ, on the Digispark board via its 6- and 3- pin connectors. It uses an Arduino Uno R3 as the programmer, and ...

I burned the boot loader with the recommended settings and the help of an Arduino Uno as ISP without any issues. Then I connected the ATtiny85 to my FTDI programmer ...