What is the part number of your Dongle? If your dongle is the newer one you must program it with CYSMART not the Bootloader Host. Here is that information from Cypress.
Also please let me know which BLE dongle is the customer using? Can you ask the customer to test the OTA with Cysmart PC 1.2? Below are the steps to test it using CySmart PC:
-> Connect the BLE dongle and Open Cysmart.
-> Press the SW2 of device and enter into bootloader mode
-> Start scan in CySMart -> If the device name came in the list. Stop scan and place the cursor above the device name.
-> Click on the upgrade firmware button in the CySmart window. load the hex file and try OTA. Let me know it is failing or not.
Thanks for the reply to my post, I used CySmart to program my device and it worked perfectly.
I believe the dongle is a CY5670 CySmart USB Dongle which is part of the CY8CKIT-042-BLE Kit.