If the ohmmeter shows a dead short, then you probably cooked the final transistors. Hopefully, you did not cook the VHF or UHF transmitter as the transistors are no longer available. Yaesu had to discontinue manufacture of the FT-847 due to loss of supply for these transmitting transistors.
GL, Ed - KL7UW
Ed et al. Those HF/50/144MHz PA transistors are 2SC5125 which are still available. They are also used in FT-857 etc... Replacement transistor used is 2SC2782 which is quite common and very cheap.
The UHF transistor 2SC3102 is not so common but modestly available.
GL, Jari OH3UW