Reported that OEM logo replacing is not working properly in webRDP 126.96.36.199
From the webRDP manual, to replace the splash screen you first need to have an OEM license. Next the following is needed :
Your banner must be in JPG format
Your banner should be approximately 1920x1024 pixels in size
Your banner must be named oem_splash.jpg
To replace the Logo, you can put in an oem_logo.png This graphic is a png to avoid the lossy properties of a jpg. If you just want to erase the logo without replacing it with your own, you can use this sample png file.
The webRDP manual can be found at the Lenovo Software support page.