I think that you cannot use u-boot from beta4 to boot the old imagefor the following reasons:
1) u-boot passes to kernel flash partitioning that would not match beta1 setup
2)you would need to put the kernel image exactly where u-boot expects it to be manually
3)you need to do some stuff to kernel in order to use it with u-boot (see the u-boot README)
3)and possibly (but I'm not sure) kernel size does not match so some stray data may be loaded along with kernel, or a part of kernel may not get loaded
You would need to make some changes to u-boot config to work around these problems.
What you can do is restore the original sharp boot loader following instructions from this thread:http://www.oesf.org/forums/index.php?showt...hl=u-boot&st=45
Then you should be able to install beta1 normally.