I found a way to make the "Last Reconciliation Date" what ever you want.
Warning this involves editing a couple files so please make a copy of all files before you edit /change anything. Or make a couple backups.
For Windows 10, goto to this folder:
Finding the file you need to open / edit in Notepad or any text editor (ex. 1110.dat = is the default for "Checking Account" Reconciliation)
Number.dat (the "Number" is the assigned number to that particular account in your Charter of Accounts, so you can double check the number there if you are unsure)
Open the file and search for LastReconciledDate and change the date after the equal sign (LastReconciledDate=2021-03-11)
Just save the file.
2nd step you may have to edit if it still does not balance: (for Windows 10)
Go to this folder:
In that folder is a CSV file that holds all you Reconciled items. The CSV.bak is your "Rollback to Previous" file of your Reconciled items.
You can edit it will notepad or a spreadsheet program (Remember many a copy of the file before you edit it)
Each line has the Date followed by the corresponding Reference Number and the transaction amount.
Delete the rows you want to remove to redo in Reconcile to help balance, or deleted everything and you can Reconcile everything from the beginning.
Please backup or make copies of these files before you do any changes.
Hope this helps. Cheers.