Cloned SSD on my Aspire XC 603 won't boot.

The the clone process wasn't successful. Put the HDD back in, fire up Disk Management and show us the partitions on both drives.

Boy, those are really weird... Was it setup for Linux at some point? It looks like disk 0 is the original and disk 1 the clone. The 1GB data partition and the 14GB New Volume are what makes the least sense, but it shouldn't get in the way of booting. Normally the EFI partition is 100MB, yours is 300MB but it looks like the clone process didn't change it much. The 600MB Recovery partition should hold the software used to do a recovery and again it doesn't look like it got tweaked. The 840MB partition should be the recovery image and it's a bit smaller than normal. What is likely happening (when booted on just the SSD) is the system looks at disk 1 and sees the 600MB partition, notices it's not EFI and stops there, rather than looking at the rest of the drive for that second partition. Less likely but still very possible is the EFI partition on the SSD is corrupted in some way, that usually only happens if the cloning process changes it's size. If the data in that partition doesn't match what's supposed to be there boot will fail. You can usually get around that by either adding the .efi file from there to the list of supported files or by disabling the secure boot option in the BIOS. Unless you are actually using them, I'd delete the D : and G: partitions and possibly use a partitioning utility to move the 600MB partition into the 1.02GB unallocated space. That will give you the 300MB EFI as the first partition, the system partition second, the 600MB recovery third and the 849MB recovery fourth. Then redo the clone process and it should give you the same structure on the SSD, but with unallocated areas removed and only the C: partition resized.