Cannot Install Os X El Capitan

  1. Cannot Install Os X El Capitan Operating System
InstallCan

Open the program called “Install OS X El Capitan” Follow the on-screen instructions. If this program is missing or will not run, then move it to the trash and empty the trash, followed by re-downloading it from the App Store. Insert the disk 'macOSX10.11.6-15G31ElCapitanDownloadedDisk.dmg'. Open 'InstallMacOSX.pkg'. Follow the steps to install the package. When the installation is over, click on the Close button and eject the disk 'Install OS X'. Open a terminal, then. Now, I've have been trying for a week and a half to get either 10.10 or 10.11 to install and I receive the same message from both: 'This copy of the Install OS X Yosemite (or El Capitan) application can't be verified. It may have been corrupted or tampered with during downloading.

Cannot Install Os X El Capitan Operating System

My machine: mid 2007 24' iMac, 2 GB RAM Intel Duo, 667MHz, 2.8GHz, 500GB HD, superdrive, OS X 10.8
The install of El Capitan, at least what I thought was the installation, took a while. A screen shows up with the 10.11 logo stating to install click continue, agree to terms and install OS, I got the option to use disk utility, time machine or recovery or click the install button. I clicked, installation (from bootable flash drive) it stated to restart, with this done a message came that there was installation media on the destination volume, try again.
I restarted and got a progress bar (Apple logo above) which never fully finished, or it did but nothing happened. After walking away for an hour or two, I powered the machine down, restarted it with the option button to get the start up disk manager but only got the apple logo and progress bar, again. I tried to start in recovery mode, also in safe mode with the progress bar appearing after each attempt.
Obviously, I cannot access the drive to remove whatever install media is present on that disk. What options do I have at this point?
Thank you
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