This firmware is only for D90SE and is NOT applicable to any other models. If this firmware is flashed to other models, it will immediately cause the product to be unusable and unable to repair by yourself. If the firmware of your D90SE is already V1.88, then your D90SE needn't this update.
The firmware version of your D90SE could be check at this tool.
What's updated:
Fixed some known issues.
Firmware and tools for Windows: Download here (Firmware and tools for Windows: Download here (This update requires a Windows 10 or higher OS with driver installed. Drivers could be download here).
Firmware and tools for MAC: Download here
If you have questions about the update of your D90SE, please contact us before updating this firmware.