Skye,
If your account balance drops below 25k at any point you will be locked out from placing any more trades.
I have personal experience of this through the DAS platform.
Intra-day, if your balance drops under 25k, you will receive an error message that basically says,
"Dear trader, because your account balance falls under the PDT minimum you cannot place anymore trades".
You will have to bring your account balance over 25k to even place another trade.
Your account will not be closed however.
Bailey Nevener
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My YouTube Trading Journal
https://www.youtube.com/channel/UCkK2SWIsYGuWm1gtlbD2C4w