grubby fatal error: unable to find a suitable template

So I upgraded kernel yum -y update kernel on my AWS EC2 base image, and I get the following:

Running Transaction  Installing : kernel-2.6.32-504.3.3.el6.x86_64grubby fatal error: unable to find a suitable template

Here is the contents of /boot/grub/grub.conf:

default=0timeout=0hiddenmenutitle CentOS (2.6.32-358.el6.x86_64)        root (hd0,0)        kernel /boot/vmlinuz-2.6.32-358.el6.x86_64 ro root=LABEL=rootfs console=ttyS0        initrd /boot/initramfs-2.6.32-358.el6.x86_64.img

So grub.conf is not getting updated, and since I already have kernel-2.6.32-504.1.3.el6.x86_64 installed, grub did not get updated the last time I updated kernel either. I tried adding the kernel manually:

grubby --grub --add-kernel="/boot/vmlinuz-2.6.32-504.3.3.el6.x86_64 ro root=LABEL=rootfs \  console=ttyS0" --title="CentOS (2.6.32-504.3.3.el6.x86_64)" \  --initrd=/boot/initramfs-2.6.32-504.3.3.el6.x86_64.img

and then /boot/grub/grub.conf looked like this:

default=0timeout=0hiddenmenutitle CentOS (2.6.32-504.3.3.el6.x86_64)        kernel /vmlinuz-2.6.32-504.3.3.el6.x86_64 ro root=LABEL=rootfs console=ttyS0        initrd /initramfs-2.6.32-504.3.3.el6.x86_64.imgtitle CentOS (2.6.32-358.el6.x86_64)        root (hd0,0)        kernel /boot/vmlinuz-2.6.32-358.el6.x86_64 ro root=LABEL=rootfs console=ttyS0        initrd /boot/initramfs-2.6.32-358.el6.x86_64.img

However, /vmlinuz-2.6.32-504.3.3.el6.x86_64 is not the kernel I entered. So I removed that and tried again with:

grubby --grub --add-kernel="/boot/boot/vmlinuz-2.6.32-504.3.3.el6.x86_64 ro root=LABEL=rootfs \  console=ttyS0" --title="CentOS (2.6.32-504.3.3.el6.x86_64)" \  --initrd=/boot/boot/initramfs-2.6.32-504.3.3.el6.x86_64.img

which resulted in this:

timeout=0default=1hiddenmenutitle CentOS (2.6.32-504.3.3.el6.x86_64)        kernel /boot/vmlinuz-2.6.32-504.3.3.el6.x86_64 ro root=LABEL=rootfs console=ttyS0 root=(hd0,0)        initrd /boot/initramfs-2.6.32-504.3.3.el6.x86_64.imgtitle CentOS (2.6.32-358.el6.x86_64)        root (hd0,0)        kernel /boot/vmlinuz-2.6.32-358.el6.x86_64 ro root=LABEL=rootfs console=ttyS0        initrd /boot/initramfs-2.6.32-358.el6.x86_64.img

At this point, I manually edited /boot/grub/grub.conf to default=0 and rebooted, and my EC2 wouldn't boot. So I tried a new instance copy and got all these same errors, so I copied the existing settings to a new entry:

default=0timeout=0hiddenmenutitle CentOS (2.6.32-504.3.3.el6.x86_64)        root (hd0,0)        kernel /boot/vmlinuz-2.6.32-504.3.3.el6.x86_64 ro root=LABEL=rootfs console=ttyS0        initrd /boot/initramfs-2.6.32-504.3.3.el6.x86_64.img

And rebooted, and it fails to boot again. Yet another try, I repeated the above but with root=/dev/xvda3, and that failed to boot as well. So at this point, I have no way at all of upgrading my kernel. What do I do?

UPDATE: I figured out the /boot/boot/ stuff, and my /boot/grub/grub.conf now looks like this:

default=0timeout=0hiddenmenutitle CentOS (2.6.32-504.3.3.el6.x86_64)        root (hd0,0)        kernel /vmlinuz-2.6.32-504.3.3.el6.x86_64 ro root=LABEL=rootfs console=ttyS0        initrd /initramfs-2.6.32-504.3.3.el6.x86_64.img

And I can successfully boot my system, however everything else about this remains true: installing a new kernel still results in "grubby fatal error: unable to find a suitable template", and grubby --default-kernel still results in no output. I have to edit my /boot/grub/grub.conf manually for any kernel update.