DIR-2660 failing to flash

Hello,
I finally managed to experiment a bit more. Eventually, the idea from tmgoblin:

provides a functional path to installing openwrt. The console didn't really provide much insight on why the recovery mode rejects openwrt. I can see the following while trying to flash openwrt:

6: System Enter UBoot to Update Img or Bin.

 abuffer(TX Packet buffer) = 0x8FFE3D40
Trying Eth0 (10/100-M)

 Waitting for RX_DMA_BUSY status Start... done


 ETH_STATE_ACTIVE!!
Got ARP REQUEST, return our IP
Got ARP REQUEST, return our IP
to check image type

=================================================
Check image validation:
Image1 Header Magic Number --> OK
Image1 Header Checksum --> OK
Image1 Data Checksum --> OK

=================================================[check_img_return:0]
image is unencrypto kernel images
*********** len: 1355, s->dataSize: 1355

whereas while trying to flash the stock image I get:

6: System Enter UBoot to Update Img or Bin.

 abuffer(TX Packet buffer) = 0x8FFE3D40
Trying Eth0 (10/100-M)

 Waitting for RX_DMA_BUSY status Start... done


 ETH_STATE_ACTIVE!!
Got ARP REQUEST, return our IP
Got ARP REQUEST, return our IP
to check image type

=================================================
Check image validation:
Image1 Header Magic Number --> OK
Image1 Header Checksum --> OK
Image1 Data Checksum --> OK

=================================================[check_img_return:0]
image is unencrypto kernel images
*********** len: 1355, s->dataSize: 1355
lost ACK
image_flg = 0, length = 17994721

=================================================

updating img...........
ranand_erase: start:180000, len:20000
..ranand_erase: start:1a0000, len:20000
...
....ranand_erase: start:12a0000, len:20000
.(5192)offs=19529728 piece=0 piece_size=37857 rc=0
Done!

and then it reboots. To me, it seems as if it silently rejects the image and stops.