prety sure your stuck with hotswapping..
i dont think error 16 will even boot a retail game. but error 13 will..
I could be wrong but i always thought it was
error 13 "no dash"
error 16, "clock time not set and No dash to set it"
I assume because it forces a clock set before it boots a retail game when stock, thats why error 16 wont let you boot retail
You could have only deleted the dash file/renamed it "whatever"
but you must either have a dead clock cap/no clock cap. or left the xbox unplugged for a while after this.. so the time died..
You should probably just abandon other tutorials you may find online as most of them are old, out dated, dont give you shaddow C and wont by pass clock check..
heimdall will make sure you do it right though.
My advice..
follow the instructions fully.
if it dosent say power off xbox or power off the pc, then dont do it lol..