99 burb radio loc

Was cleaning the battery terminals the other day and got locked out of the radio. The book says turn key on and push 1 and 4 together to get
dash(---), but that aint working. must of held for 4 or 5 minutes without success. Anyone got any ideas?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.