Before modding my radio I had to backup all the channels and banks in memory. I first dumped the memory to a chirp dump file. Then I modded the radio which erased all the channels. Then I tried to upload the channels back to the radio but I kept getting an error that the radio did not ack block 1. CHIRP is weird because it can work with so many different radios. In order to get old channels uploaded to the radio I had to download the blank memory from the newly modded radio. Copy/paste the channel data from the old dump file to the new dump file and then upload the newly pasted-to file. It worked !
I hope this might help somebody else having the same problem.
Also, when downloading the memory bank to the computer (cloning out) you have push the button on the radio after clicking the download button on the computer. When uploading, you have push the button on the radio before clicking the upload button on the computer.
To get into clone mode hold the func button while powering on. To receive data push the mode button, to send push the band button.