Dumb Trade Doubt

I've never traded before.... Yesterday I put 50 rupees in my fyers account to test trade through API just as an experiment.... bought a stock worth 37.64 but it was a margin intraday trade so around 7.5 rupees were deducted from my balance....the stock got automatically sold at 38.11 at end of session and the app was showing +0.47 as pnl....after that I had 48. something in my balance....but today morning I just got the message I'm -8.54 debit balance.... it'll be great if anyone can explain with rough calculations as to why did this happen.