if ５００ is 定金 not revenue, then book as following:

1st entry: Debit--Accounts Receivable $2000
Credit--Revenue $2000
For Recording revenue

Debit--Security deposit $ 500
Credit--liability $500(refundable)
For recording liability


2nd entry(when you receive $1500 cash):
Debit--Cash $1500
Credit-Accounts Receivable $1500
For recording cash

Debit--Cash $500
Credit--Security $500
For transfer security to cash

Debit-Liability $500
Credit-Accounts Receivable $500
For writing off liability



Now ur accounts are all balanced