Commaa 4 can't start

when I flash it, show this:

## Bug Report - flash.comma.ai

**Device:** comma four
**Serial:** a74b12f0
**Error:** FLASH_SYSTEM_FAILED
**Step:** FLASH_SYSTEM
**Last Message:** Flashing systemrw

**OS:** macOS 10.15.7
**Sandbox:** None detected
**Browser:** Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/150.0.0.0 Safari/537.36
**URL:** https://flash.comma.ai/
**Time:** 2026-07-25T18:37:36.041Z

Console Logs

```
[2026-07-25T18:37:26.826Z] [info] [qdl] Repairing GPT on LUN 3
[2026-07-25T18:37:26.840Z] [info] [qdl] Successfully repaired GPT on LUN 3
[2026-07-25T18:37:26.842Z] [debug] [ImageManager] Downloading gpt_main_4 from https://commadist.azureedge.net/agnosupdate/gpt_main_4-e9405dcd785dbe79412184e1894a9c51ab7deb33bb612166c4c42a3d2bf42a0e.img.xz
[2026-07-25T18:37:26.847Z] [info] [qdl] Repairing GPT on LUN 4
[2026-07-25T18:37:26.899Z] [info] [qdl] Successfully repaired GPT on LUN 4
[2026-07-25T18:37:26.900Z] [debug] [ImageManager] Downloading gpt_main_5 from https://commadist.azureedge.net/agnosupdate/gpt_main_5-21ae965f05b2fa8d02e04f1eb74718f9779864f6eacdeb859757d6435e8ccce3.img.xz
[2026-07-25T18:37:26.907Z] [info] [qdl] Repairing GPT on LUN 5
[2026-07-25T18:37:26.922Z] [info] [qdl] Successfully repaired GPT on LUN 5
[2026-07-25T18:37:26.922Z] [info] Repaired partition tables in 0.22s
[2026-07-25T18:37:26.933Z] [info] [Flash] "persist" partition located in LUN 0
[2026-07-25T18:37:26.933Z] [info] [Flash] Erasing LUN 0 while preserving "mbr", "gpt", "persist" partitions
[2026-07-25T18:37:28.357Z] [info] [qdl] Successfully erased LUN 0 while preserving specified partitions
[2026-07-25T18:37:28.357Z] [info] [Flash] Erasing LUN 1 while preserving "mbr", "gpt" partitions
[2026-07-25T18:37:28.369Z] [info] [qdl] Successfully erased LUN 1 while preserving specified partitions
[2026-07-25T18:37:28.369Z] [info] [Flash] Erasing LUN 2 while preserving "mbr", "gpt" partitions
[2026-07-25T18:37:28.378Z] [info] [qdl] Successfully erased LUN 2 while preserving specified partitions
[2026-07-25T18:37:28.379Z] [info] [Flash] Erasing LUN 3 while preserving "mbr", "gpt" partitions
[2026-07-25T18:37:28.390Z] [info] [qdl] Successfully erased LUN 3 while preserving specified partitions
[2026-07-25T18:37:28.390Z] [info] [Flash] Erasing LUN 4 while preserving "mbr", "gpt" partitions
[2026-07-25T18:37:28.452Z] [info] [qdl] Successfully erased LUN 4 while preserving specified partitions
[2026-07-25T18:37:28.452Z] [info] [Flash] Erasing LUN 5 while preserving "mbr", "gpt" partitions
[2026-07-25T18:37:28.480Z] [info] [qdl] Successfully erased LUN 5 while preserving specified partitions
[2026-07-25T18:37:28.480Z] [info] Erased device in 1.56s
[2026-07-25T18:37:28.480Z] [info] [Flash] Downloading systemrw
[2026-07-25T18:37:28.482Z] [debug] [ImageManager] Downloading systemrw from https://commadist.azureedge.net/agnosupdate/systemrw-8ce150ca38ef64a0885fc2fe816e5b63bae8adb4df5d809c5b318e6996366c7e.img.xz
[2026-07-25T18:37:28.711Z] [info] [Flash] Flashing systemrw
[2026-07-25T18:37:28.773Z] [error] [Flash] An error occurred while flashing system
[2026-07-25T18:37:28.773Z] [error] Can't find partition systemrw
[2026-07-25T18:37:28.773Z] [debug] [Flash] error 7
[2026-07-25T18:37:28.773Z] [info] Flashed system in 0.29s
```

Need help! appreciate it!

Start at flash.comma.ai and reproduce the FLASH_SYSTEM_FAILED report for a comma four on macOS 10.15.7, using the supplied console logs as the initial diagnostic reference. Investigate why the flash step cannot find the systemrw partition after the partition tables and device erase complete; done means identifying a reproducible cause and a verified flashing fix.

Written by the indexing model from the issue text.