If Nextion display can not be downloaded HMI file/TFT file or can not be connected or bricked,
the general way is :
1. Built an empty HMI file and compile.Using the latest version.
2. Copy the TFT file into your SD card with FAT32 format,and may sure there just only one tft file in it(Where to find the file:Nextion editor→File→Open built folder)
3. Insert the SD cart ,power on Nextion display(5V&GND)
4. Normally,the boot-loader will be back.
5. Power off and take out the SD card. Then you can try to connetct Nextion display to your computer.
5. If all above are helpless,please add a new ticket to ITEAD Support.TKS.
What is an empty hmi file?