I’ve seen the load command work in other environments, funny that it works not here.
Usually though, flashing is done via OpenoOCD’s program command, as illustrated e.g. here. With the, you should be able to e.g. do
openocd -f ~/openocd-cfg/my_ft232r.cfg -f tgt_602.cfg -c "program {firmware.elf} verify reset; shutdown;"
(assuming the file firmware.elf exists in the folder where the command is executed.)