Keeping 620 as "Positional SL", short can be initited on any rise towards channel Bottom.
In EST , one can trade short on any rise towards BO channel with SL above 602 Closing.
Break below 550 will accelerate fall. Till then , 570 then 550 will act as strong "S" temporarily for some time.
Disclaimer: I am not a qualified Technical Analyst. Please do your own analysis before taking any Investment decisions.