My Excalibur echo remote will not start my Chrysler 300 anymore, is there a reset or reprogram I can do?

Set-up (Programming) procedure is too much to type in here, and is not practical and it will differ brand-to-brand remote controls. If you wish to get more; check the sites linked here. It has set-up code list & set-up procedure to many popular brand remote controls. One among it has general set-up codes to check with TVs and other devices are given, in the order of the 'device's brand name list' in alphabetical order. Pull up older posts. Search the sites by type in the brand name to your device in its search box at the top right part of the display window. It will help you to find the document easily.
http://remotesearch.blogspot.com/
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/
http://electrohelponline.blogspot.com/
Search the site by type in the brand name of your device, in the "Search box at the top right of the Home page display" to see the set-up codes to your device, with different brand remote controls.
Programming Notes
• If your device does not respond to the remote after trying all codes listed or your brand is not listed in the code list, use the Auto Code Search method to program your remote.
• Sometimes the first code that "works" with your device may operate only a few functions of your device. There may be another code in the code list that performs more functions. Try other codes from the code list for more functionality.
This is a trial and error procedure; and quiet time consuming. You might have to check different codes said for your device.