This should do, though I did not test it. I just rewrote a few lines the other way round.
I renamed variable ACHAT (buy) to VENTE (instead of SHORT, SELL is a reserved word) to keep the french flavour.
Let me know if you have any issue.
// ACTIONS EXPLOSIVES V2
c1 = volume > 2.5* average[20](volume) and volume > 10000
c2 = close < open
c3 = close < average[150](close) and average[150](close) < average[150](close[1])
amplitude = abs(close-open)
c4 = amplitude > 5*average[20](amplitude)
c5 = close < bollingerdown[20](close)
c6 = average[15](bollingerbandwidth[20](close[1])) < 0.8*average[50](bollingerbandwidth[20](close[1]))
IF c1 and c2 and c3 and c4 and c5 and c6 THEN
VENTE = 1
ELSE
VENTE = 0
ENDIF
screener[VENTE]
Roberto