That's pretty amazing! Awesome job!
binwalk chipfirmware2.bin
DECIMAL HEXADECIMAL DESCRIPTION
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84160 0x148C0 U-Boot version string, "U-Boot 1.1.3 (Nov 23 2012 - 12:00:39)"
327680 0x50000 uImage header, header size: 64 bytes, header CRC: 0x97CD3343, created: 2014-12-22 06:23:12, image size: 4488417 bytes, Data Address: 0x80020000, Entry Point: 0x80023F30, data CRC: 0xF9349363, OS: Linux, CPU: MIPS, image type: OS Kernel Image, compression type: lzma, image name: "Linux Kernel Image"
Based on your binwalk output, it appears that the firmware image from the website doesn't start until 0x50000 in the flash chip. You should be able to start writing the firmware to the flash chip at that offset. It's worth a shot.
What is concerning though is the possibility that something in the first 0x50000 bytes has been corrupted. Since the factory firmware image doesn't contain this data, the only way to fix it would be to find a copy of known good flash image, or by dumping the flash of a known good device.