1. the bluetooth connection is invalid.

2. The system connection is abnormal and needs maintenance. Invoicing refers to issuing invoices and documents. Invoice refers to the written proof of receipt and payment provided by all units and individuals in the purchase and sale of goods, provision of labor services or acceptance of labor services and other business activities. It is the legal certificate of financial revenue and expenditure, the original basis of accounting, and an important basis for law enforcement inspection by audit institutions and tax authorities.