If your account opening application is put on hold, you will receive an email at your registered email ID explaining the rejection reason and the rectification required.
As per the SEBI circular (WEB), KRAs have to validate your Know Your Customer (KYC) documents within 2 days. Hence, if you did not register KYC at the time of signing up and are proceeding through Digilocker, you must complete rectifications within 3 days. However, if you registered KYC before initiating the account opening process, you have 15 days to complete rectifications.
If you do not complete the account opening process or rectify your forms within the specified timeframe, your application will be reset, and you will need to redo the account opening process.
You can check your account opening status by visiting signup.zerodha.com.