OTA firmwares cannot be restored to. IPSW Downloads collects them for potential future use. They might also be useful if you're doing research.
| ✗ | Apple Watch Series 2 (38mm) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | a75908506bda991e65a8a92a2b9f3da822040e1e.zip |
| ✗ | Apple Watch Series 2 (42mm) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | 11dc579c6ffffbbe2118ba8c375a0e5eab6d7279.zip |
| ✗ | Apple Watch Series 1 (38mm) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | 9e740800f9ee872e92b11ba48a90f457b4d1a4a4.zip |
| ✗ | Apple Watch Series 1 (42mm) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | f2a2415f0b9d01d3addeaaec52274b28191b339b.zip |
| ✗ | Apple Watch Series 3 (38mm, LTE) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | a5c7cb59864f1711e3dd306376f5295d22f19795.zip |
| ✗ | Apple Watch Series 3 (42mm, LTE) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | 5edf500a803d08741eea4dd93795d8c085d717fe.zip |
| ✗ | Apple Watch Series 3 (38mm) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | 0f219ee576a66c28fc9e1631ab113815366dfc67.zip |
| ✗ | Apple Watch Series 3 (42mm) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | 68ee1f40ed29827074a15095e2753b6781fbd44f.zip |
| ✗ | Apple Watch Series 4 (44mm) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | 60c09c93f6dc018bd826fa5ca7b066b1bc501179.zip |
| ✗ | Apple Watch Series 4 (40mm) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | 60354155fff1213c8eb8f51a375ec709a51e4a5c.zip |
| ✗ | Apple Watch Series 4 (40mm, LTE) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.4 GiB | d0b32a62c74d169cd5b8f3c9415e28e1170a7f32.zip |
| ✗ | Apple Watch Series 4 (44mm, LTE) | watchOS 5.3.5 (16U652) | February 18, 2020 | 1.3 GiB | fec80dc6ea499d9d32d4f72b465e00a330a5bc82.zip |